/sci/ - Science & Math

I'll start then, I've taken mechanical physics as well as a course in electricity and magnetism. Can someone give me sources to being learning about other physics that will give me a satisfactory understanding of how things work.

>>7135708

Someone else must have questions. I also want to know the difference between a moment and a torque. Also, why do they have units of energy?

>>7135724
there is no real difference
but as far as common use goes, when someone says torque, that implies there is a continuing circular motion. when someone says moment, there isn't necessarily a continuous circular motion.
so if you are spinning a wheel, you'd say torque. if you are prying a door with a lever, you'd say moment.
but again, there is no real difference, it is just a common use difference.

>>7135708
what is everyone's favorite resources when looking to read about development in various STEM fields?

magazines, websites, etc? which ones?

>>7135739
isn't torque = angular force
and moment = angular work?

How do we know quarks exist? We can ot see them, touch them, smell them, lick them or hear them, or see the effects of their gravity. How do weknow they are there?

>>7135828
no
both are sort of "effective force"

Is there a shorter term for directed acyclic graphs?

>>7135713
http://www.feynmanlectures.caltech.edu/

>>7135708
What are some good books on differential geometry past the classical differential geometry of surfaces?

And how different is algebraic geometry from differential geometry? A lot of my professors who do differential geometry also do algebraic geometry somewhat.

Can we actually see atoms? In the video below, it says we're looking at CO molecules. Now I understand that visible light has a wavelength too large to be used to visualize atoms, but could we ever actually view individual electrons or at least the cumulative cloud around a nucleus?

www.youtube.com/watch?v=oSCX78-8-q0

>>7135713
A basic physics textbook will be enough for an introduction and some deeper explanation of all parts of physics. Try Feynman's lectures or just search the highest rated physics textbooks.

Why haven't we detected a single probe, radio transmission, any kind of object or signal from a foreign planetary culture?

>>7135837
We don't know that they exist, we know that we can use them as a model

>>7135713
Nah fuck feynmans lectures, just learn modern physics on top of classical studies. Learn algebra and find a good quantum mechanics book, not griffiths.

>>7135885
whats wrong he touched you whne you were a kid?

>>7135886
I wish, Feynman is awesome, I just don't think his lectures are optimal for someone who is purely focused on progressing on the most efficient path. There are some really great textbooks that I think would be more beneficial.

>>7135896
i was talking about griffith
you definitely cannot learn a subject purely from feynman lectures
you need to solve examples and end of chapter problems
it is definitely a good resource if you read it along with a regular college textbook

Why do things appear to be smaller in a distance?

Why do so many of you believe in the standardized version of the emergence of life on earth?

There is no physical proof of it ever occurring in the natural setting.

The whole theory is just conjecture and a mess of filling in the blanks.

It's pathetic.

>>7135899
I think a more formal introduction to quantum mechanics is essential. I like how Shankar is set up: a mathematical introduction, some classical mechanics, and then instead of just "this is the schrodinger equation, here are some 1D cases for which there are exact solutions", it talks about the general postulates of quantum. I've heard other texts are good but I have only ever used Shankar and griffiths excluding references.

>>7135906
because air absorbs the light so less light reaches your eyes
.
. . things appear smaller

>>7135872
Because we've only been listening for less than 100 years.

>>7135910
>Why do so many of you believe in the standardized version of the emergence of life on earth?
No one has proof but it's a logical conclusion. Hence people will default to it because they don't know any better. That doesn't make them "wrong". Like you said, everything is conjecture, but at this point it's all we have. No one will come out and claim it's 100% true, but at the same time you can't deny that the scenario has a probability of being true.

Aliens could have started life on earth. Time travellers from the future could have come back and accidentally started life in some sort of paradox. God could be real and have done it. Timelords could be real and have done it. Who knows? All of those scenarios are "possible" but we choose to agree with the one that is most possible.

>>7135759
nobody? this seems like the easiest one

>>7135929
>insinuating there is a single person on /sci/ who knows or cares about anything related to STEM
lol

>>7135910
>>7135926
http://en.wikipedia.org/wiki/Miller%E2%80%93Urey_experiment

Question: UK has a solar eclipse on Friday. News/weather/talk shows all say "dont look at the sun" you WILL go blind.

How many people do YOU know who have gone blind looking at the sun? Its been there 4 billion years, havent we evolved against this?

>>7135966
Have you ever looked at a light bulb for a while, then looked at a dark surface and seen the brightness burned into your vision?

If you stare a small light source and keep your focus on it, you don't notice the fact that your eyes are getting burnt out. Look for long enough, and you can do irreparable damage.
Pretty unlikely you could completely blind yourself, but it's certainly possible to induce partial blindness/generally fuck up your vision.

>>7135966
It's pretty much impossible to look at the sun when its at its brightest. Don't fuck with it.

>>7135966
I just want to know why the sun during a solar eclipse has stronger blinding powers than normally.

>>7135966
>havent we evolved against this?
Yeah, by being smart enough to not look at the sun for too long

Also that is not how evolution works

>>7135983
It doesn't, but for some reason people think it's okay to stare at the fusion machine that provides (directly or by proxy) 90% of the energy used on this planet, just because 3/4 of it are covered by the moon.

If putting your hand in fire is bad for you, why would putting a smaller fraction of your hand in fire suddenly be okay?

>>7135983
Because it gets dark, which causes your eyes to dilate to take in more light, but the edges of the sun peeking around the eclipse are as bright as normal, so you end up taking in more light from looking at it or something.

why did the janitors kill the philosophy containment thread?

>Can the Universe lose track of what it's doing and break it's own rules?
>>7133617

>What does /sci/ think, are there other living creatures out there or are we it for the whole universe.
>>7133318

>What is the set of all sets?
>>7130979

>how many of you /sci/entists believe in God?
>>7135055

>mfw just realized humanity's biggest problem is aging.
>>7132754

>nostradamus was right
>>7135199

>What is love /sci/
>>7127202

>What Neuroscience will tell us about Moral Responsibility
>>7135430

also
>stupid questions that don't deserve their own thread thread?
>>7133383

>>7135869
You can't "see" atoms obviously, but you can see their shadows, pic related is Ytterbium atom, this is a visible light spectrum photograph.

There's also ways we can image the orbitals:
http://io9.com/the-first-image-ever-of-a-hydrogen-atoms-orbital-struc-509684901

>>7135929
>>7135759

For my own field, our professional organizations send me a newsletter every month and I keep up by talking to my colleagues and reading review articles published in journals.

Don't read shit written by journalists, they're useless, especially the popular science journalists.

>>7135995
>If putting your hand in fire is bad for you, why would putting a smaller fraction of your hand in fire suddenly be okay?
Smaller heat transfer area so far less damage would occur in total, depending on the circumstances heat could be transferred fast enough from your hand to maintain a steady state temperature only slightly above your normal surface temperature with absolutely no damage occurring.

>>7136009
Because it's not /sci/.

>>7136023
Sound's interesting, but over my head. When you say we can image their orbitals, you mean the path the electrons travel?

I have no understanding of wave functions and imagine atoms as a solar system/peanut at the center of the stadium etc.

>>7135910
Even if it didn't occur naturally on Earth then it occurred naturally somewhere else.
Also why would aliens seed a planet with only bacteria? How boring.

I purchased Mathcad 15 and Prime 3 from my university. My professor suggests that we use Prime 3, but people say it's shit. Ought I use 15 instead, if Prime is crippled, or am I setting myself up for failure?

>>7136050
The wave probability function yes, you can read up on it in any modern introductory chemistry or physics textbook.

>>7136050
imagine you have a shotgun and you shoot it at a target over and over. This will create lots of little holes that together have some kind of spread pattern. That's the wave function; that pattern. If someone now shoots a shotgun where the shell has only one ball bearing then you can give a probability of where that bearing is likely to hit the target.

What is the evolutionary benefit of enjoying dank memes?

>>7136399
there is a whole book about that
the selfish gene - richard dankins

>>7136399
>4chan users
>evolution
ayy

>>7135919
stop HAHA

Physics bros,
Why is the net force on this closed circuit in a magnetic field zero?

>>7136536
>Physics bros,
>Why is the net force on this closed circuit in a magnetic field zero?
use the differential lorentz force and integrate (though if you are smart, you wont have to)

>>7136536
cuz flux = 0

>>7136536
if you have a UNIFORM B field, the net force is ALWAYS ZERO
you will have a torque on the rectangular frame and it will spin around the axis y=c, z=0 line

to find the torque in a uniform b field, you need to find the magnetic moment (m) of the frame, which is current*surface area, where the unit normal of the surface area is found by the right hand rule of the current then you do a cross product m x B to find the torque

if the area of the frame is A, its unit normal will be (for abc unit vectors for xyz) c and the unit normal of b is b so you have
I*A*c (cross) b * B so -IAB a

>>7136540
>>7136551
ah so because both the circuit and the field are static the magnetic net force is 0, no? makes sense
>>7136580
kek you answered the follow-up question of what the torque is

thanks anons

>>7135708
Is it possible to make something 100% pure

I'm modifying a polymer with small molecules, but even after dialysis, tiny impurities remain that is fucking me over for my next steps.

I'm a garage chemist sort.
I mostly do energetic materials but I also do a little bit with metallurgy and my current project is setting up a homebrew arcwelder/smelter setup.

In the process of getting parts for this I needed to drain a battery, and I was bored, so I tried to do some electrolysis to fill a condom up with some hydrogen/oxygen just because.

I mixed in some salt to get better conductivity out of my water, but that wasn't working, so I sanded down some brass (spent ammo cartridges) and hooked them up to my leads for better surface area. It started to bubble way more noticeably but the water immediately began forming cloudy shit and some dark green algae like stuff appeared. I immediately disconnected it from the electrical supply and sealed the lid on my glass container.

I think this shit is some kind of cupric chloride but I've got no idea and I don't know if it's dangerous or not.

I think the lid was contaminated with some pyro grade aluminum of very fine mesh, and after sitting overnight it's turned bright yellow/orange....

anyone know what the fuck this is?

It also appears the brass itself is turning orange.

>>7135759
>various STEM fields?

phys.org

>>7136814
100% pure at a literal level is impossible, but given enough filtering and washing you can get it to a practically pure level.

There are other ways of doing similar process where the end result is that you react the contaminants off with something that won't react with what you want to keep in a non-reactive container to get either two substances that don't react or one that you can filter off, but those tend to be a bit more technically complex....

>>7136845

>>>/diy/

>>7136872

Seemed like a chemistry question to me.....

And I'm pretty sure chemistry is a science.

>>7136861
>react the contaminants off with something that won't react with what you want to keep
though it likely won't work with my case, that's certainly a clever approach to try in the future

>>7136199
Oh damn, that's helpful. So in pic related, the red center is the nucleus and the blue misty part is the location where the electrons are most likely found?

BS in Physics here. Any good suggestions for companies to work for?

What is microsoft redistribution 2008. i Have lot of them/ Dn't knw if useful or useless. i knw these are libraries but why there are so many parts of it. can't it just be under the name 2008. And if new libraries come make it 2009 and replace the old one. ITs like piling shit.

>>7136925
Get internship at CERN

>>7136876
Your question is pretty difficult to answer, since you have a lot of stuff going on in your jar. You might be better off making a thread here or on >>>/diy/.

Sorry I can't be totally helpful. I do have some safety advice for you.

Never seal a solution that is producing gas, or is undergoing any type of reaction. If you didn't know what was happening, you didn't know if it would stop when the lid was sealed. If you were concerned about breathing in the gas, then you don't have proper ventilation. There are ways to build fume hoods for your garage (ideal), or you could just open the damn garage door (gets the job done).

>>7136914
Not quite. The picture you have is the wavefunction of hydrogen, it has 1 electron. What's shown is basically the "shotgun spread", and the colours indicate the intensity (number) of points. So the red part means that you have lots of hits there, yellow/green means there are a good amount of hits, and blue a few hits. This makes sense since the electron (and there's just 1 in hydrogen) is most likely to be found near the nucleus.

What makes microwaves and radio waves so much better for communication than other types of electromagnetic radiation? My physics teacher basically said "they travel through things easier", but I'm looking for what makes that possible.

how is there so much energy in food
where does it go

>>7136977
Chemical energy stored as sugars, fats, etc.

>>7136977
food is basically a bunch of molecules, your body first breaks them up into smaller molecules that are easier to do chemistry with, then they use those molecules in various chemical reactions which are usualy exothermic (they give energy). They also make other things like ions and stuff that gets used to make amino acids(building blocks of proteins) and proteins(hair, muscle fibres,...) etc.

Basically your cells are chemistry PHDs+++ experts that can convert pretty much any substance you put into you and also their reactions are perfectly chosen so that you don't blow yourself up from the inside.

>>7136968
Sweet. It'd be interesting to see one for H2O or something similar where the electrons are pulled by the more electronegative atom.

Follow up question; though the probability is rare, what would make a hydrogen electron move further out and be in the blue region? Absorption of energy, making it jump orbitals?

Do pulsars pulse in the visible spectrum?

>>7136999
yes it needs to absorb a photon with a certain amount of energy to move further away from the nucleus. But even though it can theoretically go infinitely far away, if it moves too far from the nucleus it will either come back down (and emit a photon) or it will be taken by another atom(leaving the hydrogen atom to become a hydrogen ion H+).

>>7135708
Should I go CS/Physics, or CS/Math?

I'm slightly more interested in Physics.

>>7137045
for example in NaCl you have an ionic bond, that basically means that an electron from Na (one that's furthest away from the nucleus) gets captured by the Chlorine atom. So now you have Na+ (it lost an electron) and Cl- (it gained one). And even though it's weird that these atoms aren't normal like that, it actualy makes them more stable. It also basically turns them into magnet ends since one's + and the other's - so they attract and stick together giving NaCl (salt).

>>7137012
Most pulse radio waves, but some are known to pulse with visibile waves.

>>7135998
I was excited to read how long it took for someone to provide the actual answer instead of smug ignorant confidence that it's false.

It goes to show how ignorant and uneducated people are for it to go unanswered that long. Unbelievable. Why the fuck am I even here?

Why is women's skin significantly softer than mens?
>Hormones, mostly estrogen
Yeah I know that but why? Why and how does estrogen work that way?

>>7137054
Math/Physics and learn CS on your own. CS is far easier to learn by self study and the classes go way slower than Math/Physics.

>inB4 someone implies I'm just talking about programming and not the theory side too

>>7137095
What if I want a Software Engineering job right out of college?

>>7136936
Well it's a library of functions and stuff (think std library in C++, but this on has dlls). There are so many because sometimes installers a shit and reinstalls shit you already have because of a slight version difference.

>>7136845
Use a gas-chromatography- mass spectrometry.

>>7137092
lotion?

>>7135983
Because now people are staring at it.

Hey /sci/

Is there softwares more suited for the creation of technical documents?

How would you go about creating something like pic related with diagrams, nomographs, equations, charts...?

displacement is the derivative of energy with respect to mass
RIGHT?

I want to finish Linear Algebra and Real Analysis, and I have only 2.5 months left. I have to go to school, which means I don't really have all day to do maths, as well as serious demotivation because school tires me out... It doesn't tire me out because it's hard, but on the contrary, because it's seriously boring (and easy mostly). Now, I can't study this summer which is why I only have 2.5 months. Can I manage to finish, and what should I do? Also, should I skip exercises, and what should I do when I find that they're taking a huge portion of my time? Thanks. (Finished most of the part of single-variable analysis, though I need to revise some stuff.)

I want to self learn Electrodynamics

What do I do

I have done Real Analysis/Linear Algebra/Vector Calculus/ODEs

Is l'Hôpital's rule supposed to replace any and all methods for finding the limits to problems when there's an indeterminate?

>>7138131
Bring homework to class (if possible), do them if you aren't needing to pay attention in order to do in-class work?

>>7136845
Could be a lot of things but I'd wager it's things getting oxidized since you still got it after you cut the electricity so I doubt it's very dangerous.

>cupric chloride
Highly doubt it, but I wouldn't risk it anyway. Most chlorides are pretty dangerous if vapourized, but harmless as a solute in water.

>>7138164
Any EM book. You are well prepared, especially with real analysis.

>>7138170
I don't really pay attention in class ( except in chemistry because I suck at it (Mostly because I have to write out every single detail)), but I get scolded by teachers if I do something not related to what we're taking in class (got kicked out of class once...) and then focusing is hard. Do you think I should focus on reading theorems or on solving exercises? How do I strike the right balance if i have such litlte time?

>>7135837
Deep inelastic scattering is one big piece of experimental support.

>>7136971
Permeability is absolutely essential for obviously reasons, as a rule of thumb less things are permeable to higher energy EM waves, for example IF frequency can cause atoms to vibrate (and is caused by cessation of atomic vibration), x-ray can ionize atoms by knocking valence electrons etc.

A good text that explains the different spectra's interactions with matter is is Skoog et al. "Principles of Instrumental Analysis". Get it now because you're going to get it anyway at some point in your career.

>>7135864
acyclic digraphs

>>7137054
Honestly don't listen to the other anon, CS is far more employable and shiny on a CV, it should be obvious that you should "study what you enjoy" in your free time, but don't let it interfere with your professional career.

University is not for hobbyists.

>>7137092
I'm not an MD, but I'm pretty sure it's mostly because it's fattier (heightened fat levels because of estrogen).

For example feel the muscles on your forearm (gently) and even though you are barely pressing at all the skin feels hard, then feel your ass, again barely touching it, and notice how soft it feels.

If you don't have any fat on your body, go find a women to grope.

>>7137099
>What if I want a Software Engineering job right out of college?
Study software engineering, why are you even asking this question? You can't get a SoftE job with a Physics degree no matter how much the department's dean tried to shill that you can, don't be one of the idiots that get tricked into studying it.

>>7138111
>Is there softwares more suited for the creation of technical documents?
LaTeX is the most commonly used software for compiling the final .pdf document, it's easy to type in equations and for including vector graphics figures that will be spaced and organized on the industry standard for you (if for example your figures and tables pop up a few pages later than you intended, don't try to change it, it's perfect the way it is because it's been like that in professional publications for almost a century).

For actually drawing the figures themselves there's many things you could use. Generally raster figures (.jpg .png etc.) are considered unprofessional so you should get used to drawing vector figures. For a general open source vector drawing tool I recommend InkScape, for quickly drawing technical diagrams and flowcharts it's probably better to use MS Visio for now because of the built in capabilities.

>>7138200
>CS
>Employable
Top kek. CS is one of, if not the most over saturated STEM course right now.

It certainly is NOT more shiny on your CV if every fucking cunt is doing it.

It's not that CS is inherently bad, but there are far too many people (read: inadequate) doing it right now.
Unless you are aiming to be in at least the top 5% of your class, and maybe even do a masters afterwards, it could be a massive waste of your time.

CS graduates certainly do find jobs easily, but they have nothing to do with CS. They are just office monkey jobs for people who can use MS excel and access.
Physics grads have lower employment stats because they're generally more picky and don't want to take on office monkey positions.

If you just want a job do CS. If you want to enjoy your work and enjoy the subjects, do physics/maths.

>>7138242
> excel
> fucking access?
So you have no idea what you are talking about?

>>7135868
>And how different is algebraic geometry from differential geometry?
Really rather different. The basic object building block in differential geometry is R^n, and the functions on this space that we care about are smooth. From R^n you glue together other differential manifolds, such as making a circle by gluing together two bits of string. These resulting manifolds have to be smooth.
In algebraic geometry, we are concerned only with spaces that can be cut out of F^n by polynomials, i.e F(X,Y,Z) = 0. The functions that we care about o this space are polynomials defined on it. The first difference is that we no longer focus on real objects - algebraic varieties as they are known can live over any field (or ring in the modern theory). These varieties do not have to be smooth; consider <span class="math">x^3 + x^2 = y^2[/spoiler].
The methods are very different, while the differential geometry relies on the properties of smooth functions and their derivatives, and differential equations/forms, the algebraic theory uses on polynomials, and the properties of special rings and fields built from these polynomials. This is why is i called algebraic geometry - it's the use of abstract algebra in its study that lends it its name, not the fact that its objects of study satisfy polynomials.
That said, there are many similarities between the two and one has much to gain in translating the straight-forward techniques of the former to the abstract mess of the latter.
This only touches classical algebraic geometry; the modern theory is much more abstract and ideas from diffy geo seem even further away.

>>7138247
Do you really think the bottom 50% of CS grads are getting jobs that anyone with any degree couldn't do just as well?

There are decent Cs jobs, but nowhere near enough demand for all the graduates at the moment. The competition is fierce.
The kinda jobs they get are still IT related, just nowhere near what most people expect from a CS job.

Small companies use excel and access for serious business, and don't really expect much better from employees. I didn't say it was a good thing, but there you go.

>>7138164
>>7138182
electromagtecist here (what would that even be called..)
what the fuck does electromagnetism have to do with real analysis

>>7138168
no
it only works for 0/0 or inf/inf and sometimes it just doesnt work and taylor expanding is easier
i cant think of an example though

>>7138255
the ol' saying

good programmers are highly desired

>>7138242
I'm specifically talking about good universities, not IT degrees labeled as CS.

>Physics grads have lower employment stats because they're generally more picky and don't want to take on office monkey positions.
That's complete bullshit, most Physics grads never end up working in a technical field, if you don't believe you can check out the thread on PF that's been up for over 3 years. I like physics, but it's definitely not an entrance degree to a professional STEM career.

>>7138255
> Unless you are aiming to be in at least the top 5% of your class
> Do you really think the bottom 50% of CS grads are getting jobs
wow. that's quite the goal post motion.
> The competition is fierce.
It's fairly common for recruiters to come and do everything to get YOU to go work for them.
This is pretty rare outside CS.

My brother did CS at a top 10 school and ended up having top companies compete over him. And there's plenty of not so great companies that need coders as well.

Pretty sure Access has been dead for the past 10 years. We only use excel for filling out forms and because it works on macs.
I have seen CS majors end up as sysadmins though. Your sensationalism just seems inaccurate.

>>7138229
> http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0115069
> We show that LaTeX users were slower than Word users, wrote less text in the same amount of time, and produced more typesetting, orthographical, grammatical, and formatting errors. On most measures, expert LaTeX users performed even worse than novice Word users.

>>7138255
>still IT related
CS isn't even IT related. Also most engineering consulting firms would hire CS bachelor holders over Math PhDs, that's how valuable a CS degree is.

>>7138273
Again, "technical field" is a very wide term that now includes shit like support call centers and general admin shit, because it requires "technical knowledge" i.e. how2computer.
These are no more STEM careers than the physicists going into unrelated fields.

>>7138278
> produced more typesetting, orthographical, grammatical, and formatting errors.
duhhhhhh

you use LaTeX so your paper doesn't look like shit.

>>7138254
Not him, but thanks for this post, very informative.

>>7138283
>"technical field" is a very wide term that now includes shit like support call centers and general admin shit, because it requires "technical knowledge" i.e. how2computer.
Are you fucking high? You are literally acting like that stupid relative that thinks technicians are the same level as scientists.

When we're on /sci/ you're supposed to know what we mean by technical PROFESSIONALS.

>These are no more STEM careers than the physicists going into unrelated fields.
Once again, go read the study in that PhysicsForum thread, 80% of CS majors find profesional work in their field and virtually100% of engineers end up in engineering and tech management while Physics graduates mostly end up in unrelated office jobs if they don't attend grad-school.

>>7138276
I was hoping you could fill in the blanks yourself. I won't assume you're capable next time.

I'm saying the bottom 50% basically don't have a Cs degree. They have a degree, sure, but it might as well be in liberal arts.
For the 50-90% of the class, they will be able to get decent positions, but there is intense competition. I didn't say there are no jobs, but less than the numbers applying.

For the top 5-10%, you will be sought out by employers and can pretty much pick your boss.
The problem is if you mention this then people immediately go "hurrr well I am clever so das me mayne" but that's simply not true for everyone, even on /sci/.

As for the recruiters, yes they do come and look for grads for positions. What they don't tell you is how many other institutions they have also gone to to advertise the same fucking positions.
There are usually a minimum of 50 applicants per position for the big firms that are rich enough to pay for a recruitment process like that.

>places I've worked have never used access, so nobody uses access
They do, they really really do. Some companies still rely on XP for fucks sake, of course they still use 10 year outdated software.

>>7138278
What is the point of your post? No one said it was faster though in certain aspects it can be faster for experienced TeX users especially for quick documents. The point is LaTeX is more professional and most journals don't even accept Word.

Also try writing a 200+ page technical document in Word vs. convenient object orientation in LaTeX, if you've never experienced frustrations like screen freezes and lag prepare your anus.

I'm stuck /sci/, i have to measure the Cu2+ in a water sample through spectroscopy, to do this I've got to make a calibration line, but I'm stuck on getting the right concentrations to use. I'm using the Beer-Lambert law to determine the concentration to get an extinction of 0,1 (minimum) and 1 (maximum), but for some reason I feel like I'm getting the wrong answers out of this.
I'm gonna use a coloring with ammonia for this, which gives the molar absorptivity of 68,8.
if I'm correct the minimum should be 0,001453 mg/L and the maximum 0,01453 mg/L
could someone please tell me if I'm correct or not

>>7138302
>I'm saying the bottom 50% basically don't have a Cs degree.
Right, and the bottom 80% of physics and bottom 95% of math doesn't have degrees either, so what's your point?

>>7138296
>Are you fucking high? You are literally acting like that stupid relative that thinks technicians are the same level as scientists.
Just because we know the difference doesn't mean the HR people advertising positions do.
A lot of office jobs are giving them fancy titles and adding requirements for technical degrees just so that they don't have to do the basic IT training for new hires.

People take the jobs, work our that they're shit, plan on leaving shortly but then soon get comfy with the minimal workload since they can just automate stuff and finish a day's work in half an hour.

>Once again, go read the study in that PhysicsForum thread, 80% of CS majors find profesional work in their field and virtually100% of engineers end up in engineering and tech management while Physics graduates mostly end up in unrelated office jobs if they don't attend grad-school.

I'm not arguing with the numbers, I'm just saying that it's much easier to claim that work is in your field when it really isn't for CS, so I'd take it with a pinch of salt.

I did EE because going the same route would be harder through physics. But I definitely would have done physics over CS if I had to make that decision.

>>7138315
>[citation needed]

>>7135708
>QUESTIONS THAT DON'T DESERVE THEIR OWN THREAD
welp i guess it is now
battle of the majors

>>7138296
>technicians
Literally the modern technician is a degree field called mechatronics, look it up.

Now that every job needs either 20+ years of experience, certifications out the ass, or a degree if you want to make more than $15 without breaking your back, even if someone's only job is to tell the difference between a hammer and a screwdriver they need a two year degree and 3 years relevant work experience.

>>7138164
Griffiths Electromagnetism is a particularly good text for this

>>7137092
You can find plenty of information online, mens skin has more structural proteins or something like that. It's firmer, but it harder to cut and relaxes more slowly, which is why women get more wrinkles early.

>>7138280
>implying an engineering firm would ever hire anyone but pure breed engineers

>>7138318
>I'm just saying that it's much easier to claim that work is in your field when it really isn't for CS, so I'd take it with a pinch of salt.
Sort of agree, but the CS majors from good schools never end up in those jobs, it's IT degrees which crappy schools label as CS that get IT jobs and everyone knows which schools do which.

>HR
HR knows, they have algorithms that run degrees and universities through filters, that and you're pretty naive if you think someone spent 3 years of their life on a degree and still don't know what they're worth, they don't take IT jobs unless it pays as well as a CS position. The reason HR knows is because most companies only hire from universities they are familiar with, which is why faculties without industry connections have the lowest employability rates for their graduates.

>I definitely would have done physics over CS if I had to make that decision.
Well unless you were planning on also attending grad-school or trying to transfer to engineering that would be the biggest mistake of your professional career.

>>7138321
My citation is "numbers I pulled from my ass" since that's apparently what we're doing or did you not get my not-so-subtle mocking undertone?

>>7138329
Everything about your post is completely wrong. Mechatronics is an accredited engineering profession, you can check the ABET website.

For every X engineering discipline there is a less theoretical equivalent X engineering technologists and even less theoretical X engineering technician degree. Technicians are the only ones that need to stack certifications, for obvious reasons.

Everyone in industry and STEM academics knows and understands this (except you and half of /sci/ apparently).

>>7138258
It shows a level of mathematical maturity.

>>7138336
I need someone to fetch my intern's coffee so he's wakeful enough to fetch my coffee.

>>7138353
let me guess, you are a provefag with no understanding of electromagnetism
in reality, real analysis will have absolutely no effect on your electromagniticization abilities

>>7138340

>Sort of agree, but the CS majors from good schools never end up in those jobs, it's IT degrees which crappy schools label as CS that get IT jobs and everyone knows which schools do which
If everyone knows, then why do people take courses at those places at all? It's not so clear to everyone that these things matter, so I'm giving the average of the good and the shit schools combined.
If someone is in a position to have a fairly free pick of their course options and where they go, chances are employment in their chosen field won't be a problem no matter what they do.

>HR knows, they have algorithms that run degrees and universities through filters, that and you're pretty naive if you think someone spent 3 years of their life on a degree and still don't know what they're worth, they don't take IT jobs unless it pays as well as a CS position.
>The reason HR knows is because most companies only hire from universities they are familiar with, which is why faculties without industry connections have the lowest employability rates for their graduates.
If that is your experience, consider yourself lucky. I certainly know many people who have taken degrees with little consideration to where it leads or it's value. Welcome to 2015, where everyone has a degree and at least half of them are worthless.
People spend 3 years doing it because it's better than unemployment. We live in a world where people put themselves in debt to buy gadgets they can't afford, of course there are dumbfucks doing worthless courses. The schools fucking love the extra money.

>>7138369
>>7138258

I'm pretty sure they're talking about QED, not EM.

>>7138276
> Pretty sure Access has been dead for the past 10 years. We only use excel for filling out forms and because it works on macs.
Nope, and nope. Access is still alive and kicking. I work for a major utility, and we use it all over the place. We've got Oracle DBs for our major stuff, but Access is still pretty pervasive in the small office environments. It's not as common as it once was, but it's still there, mostly because it's really nice for building quick web interfaces to DBs, and it plays nicely with Excel.

Excel has been used extensively in every industrial workplace at which I've ever been employed. In addition to the utility I'm at now, we're talking a couple of real-time oil industry labs, a pipeline operator, a spectroscopy software company, a pharmaceutical manufacturer, a chemical manufacturer... and a library. (Fuck, have I really had so many jobs?) It's really very useful. Anyone can learn it and build their own tools. There's something nice about not having to wait for some software engineer who doesn't know shit about what you do to build something that helps your day-to-day work.

>>7138376
oh shit...
but it was ambiguous
then I have absolutely no understanding of QED so I do not know whether or not real analysis would be of any use

>>7138375
>then why do people take courses at those places at all?
Because some people actually want and IT job, actually the majority do because they don't want to do difficult degrees (to them) like CS. The people who do these type of degrees where average HS students who don't even know what real uni Physics or CS is, most of them will get hired into a crappy IT job and the rest will be unemployed.

>so I'm giving the average of the good and the shit schools combined.
Well fine, but when CS is mentioned on /sci/ we generally mean the proper CS schools just for your future consideration.

>Welcome to 2015, where everyone has a degree and at least half of them are worthless.
Pic related, there are far less STEM degrees than you probably believe, to extrapolate annual stats consider that roughly 60-70% of Americans have a degree, so now you can see that % that actually has a STEM degree. It's far more than half that are useless, but CS is definitely not useless, even the crappy CS degrees.

>>7138306
The point was partly trolling, but partly to point out that "more suited to the creation of technical documents" doesn't apply to LaTeX as much as you might think. If you're just starting, it's better to use Word. If you're an expert... it's just as good to use Word.

> most journals don't even accept Word
Bullshit.

>>7138340
cont.
>Well unless you were planning on also attending grad-school or trying to transfer to engineering that would be the biggest mistake of your professional career.
Again, in your experience. CS grads are not equally valuable everywhere. I'd say physics is on average not quite as valuable, but is more stable. The demand for CS varies wildly from region to region.

>My citation is "numbers I pulled from my ass" since that's apparently what we're doing or did you not get my not-so-subtle mocking undertone?
For the sake of argument, let's just say that the lower 50% of CS and physics grads are equally dumbfucks who shouldn't be in school but flipping burgers.
I'm sure someone will say one should be slighter higher than the other, but I really don't give a shit, roughly 50/50 potentially useful/worthless degrees, right?

But the stats for CS employment say that 80% find professional work in their field. Does that not sound extremely fishy?
You're gonna happily eat up that 80% of ALL CS majors are good enough to find directly related jobs?

Why isn't everyone doing CS with such great employability stats like that? Oh wait, they are, and that's the fucking problem in the first place.

Everyone likes to exaggerate their job. HR payroll people will say their job involves accounting, and people working on phones for tech support will call, their jobs "technical" even though it's just following a script.

>>7138350
Mechatronics is a technicians degree. You're a moron if you actually think Mechatronics is worth anything than basic work experience. It's literally for people who were coddled their whole life to learn not to touch live wires and to watch their hands when using a hammer. Try and justify how a Mechatronics degree is not the same exact kind of degree that "business management" is for a manager at Starbucks.
>b-but muh cybernetics/IoT/whatever stupid bullshit!
Any moron can plug shit together and put things where they need to go. Businesses just need some insurance if the idiot fucks it up.
>were're not responsible the guy used 240V instead of 120! he was educated so it's just one of those unpreventable accidents!
The fact you actually have to get an accreditation shows how much of a joke the degree is.

>>7138388
>Well fine, but when CS is mentioned on /sci/ we generally mean the proper CS schools just for your future consideration.
If someone is asking /sci/ for course advice, you can't be sure they know the difference.
To assume everyone on /sci/ asking about CS is going to a top tier school would be foolish.

>It's far more than half that are useless, but CS is definitely not useless, even the crappy CS degrees
It's not useless because the degree is bad, it's useless because nobody sane enough would want to employ someone from the bottom half of the barrel given the choice.
And if they were, you'd have to wonder why they don't mind.

>>7138389
Technical documents require precise considerations and the elimination of ambiguity, why would it be better for people to type it faster?

>If you're just starting
It takes a weekend to learn LaTeX, this is a shitty excuse that I only ever hear from undergrads or lazy post grads. You can't even add vector graphics to Word, it's terribly inconvenient to include graphics from your simulation/programming package into Word while with LaTeX you can automatically parse your strings to \include newly generated figures captions and all.

>Bullshit
It is in my field, I've never submitted a .docx and I don't think anyone in my department has, it's an extreme pain in the ass to change a word document into the correct template required for publishing while .tex files require you to copy-paste 3 preambles. I have seen journals specifically request only submitting editable .tex files.

The only reason people still use Word past high-school is because they refuse to get out of their shell, this is very unbecoming of someone who should be trying to challenge themselves every day.

>>7138402
Baiting and "pretending to be retarded" should be a bannable offense.

>>7138392
It's not fishy because you can just look at the salary stats to see most of them are working proper CS or very high paying IT (which, really a CS would happily take). So even if they reported CS while they're actually doing CS it's still fairly high paying even if not CS and worth studying.

The difference is that only a very low % of Physics graduates report Physics salaries while most of them aren't even claiming to work as a Physicist at all.

>>7138404
>If someone is asking /sci/ for course advice, you can't be sure they know the difference.
If someone is asking for career advice on 4chan they deserve everything that's coming to them.

>>7138421
(Forgot pic)

>>7138421
Things are very, very different in the UK, and Europe in general I would imagine.

http://www.theguardian.com/higher-education-network/blog/2013/sep/16/computer-science-graduates-unemployment-bme

https://cphcuk.files.wordpress.com/2013/12/cs_graduate_unemployment_report.pdf

Given that the US is to giant compared to lowly eurpoor land, I assumed a lot of variation in actual employment levels from state to state.

>>7138454
>Caring about shit outside the states

This is where all the money is, unless commies would stay in a socialist shit hole instead of coming here to earn some real money.

>>7138458
>earn $100k/year
>spend $20/year on tax even though you get nothing out of it
>spend $40k/year on family healthcare
>spend $5k/year on gas because everything is 50 miles away
>spend $15k/year on mortgage repayments
>spend $10k/year rebuilding your house because everything is made of plywood and hurricanes wreck it good
That leaves you with $10,000 for all your food, utilities and everything else

Gosh, I wonder why it's only mexicans flooding your country.

>>7138485
>>spend $20/year on tax even though you get nothing out of it
You get to watch Arabs being BTFOed
>>spend $40k/year on family healthcare
>On 4chan
>family
>>spend $5k/year on gas because everything is 50 miles away
Fuck yeah.
>>spend $15k/year on mortgage repayments
At least you can actually own a house as opposed to renting a shitty flat in europoorstan
>>spend $10k/year rebuilding your house because everything is made of plywood and hurricanes wreck it good
>Living in the flyover states

>>7138494
>flyover states
>hurricanes

wut

>>7138498
Somehow read tornadoes, heh, whatever I prefer some excitement of shitty calm cloud weather my entire life.

>>7138494
Switch the family healthcare for enough booze and hookers to take your mind off your forever alone life.
Any difference will be made up from the extra medical bills from your STDs.

Mortgage payments are basically the same as rent here anyway, only difference is the initial down-payment.
Anyone renting long term is the definition of retarded if they plan on settling down, or so poor they don't belong in the conversation anyway.

If the house is still standing, it still needs the walls replaced or the foundations being fixed or various other things.
Americans can't build a house to last for shit.

>>7138510
>Americans can't build a house to last for shit.
Truth tbph.

>>7138559
>>7138510
>can't build a house to last for shit
Tell that to my asbestos pipes and radiators fucker not online see what happens.

The only time houses degrade is when le happy merchant landlords don't take care of anything, or the houses are occupied in black neighborhoods where they'll steal the fucking plumbing from the wall if you tell them to pay rent.

A house is also a lot easier to manage when it's 92m^2 compared to our houses easily being more than twice as large. Eurotrash also has to deal with the government literally telling them what shutters you need on the windows if it's an "historic" area.

>>7138585
>an "historic"
Confirmed for retired old fuck sitting on porch, telling kids to get off his lawn

But seriously, part of the reason our houses cost so much for their size is because they are built to last without a lot of maintenance.
Short of repainting some surfaces, replacing lost tiles and fixing buster guttering, there isn't anything to maintain unless it is purposefully fucked up.

Your homes just seem to fall apart in a few years if you're not actively taking care of them.
Have seen places get some serious fires, and all they had to do was redecorate the inside and it was good to go, structure untouched.
You try redecorating a pile of timber ashes.

An induced matching is a matching such no edges exist connecting matched vertices except for the matching edges.
I want to prove that for any graph, the number of edges in an induced matching can not be greater than the size of the maximum independent vertex set.

>>7138599
> Your homes just seem to fall apart in a few years if you're not actively taking care of them.
what? Are you talking about American homes?

You watch too much news. Only reason houses around here get destroyed is from different sorts of natural disasters.
Both my sets of grandparents have been living in the same house for the past 30 years or so.

>>7138340
>implying schools are relevant when it comes to computer science

In movies, pop culture, scifi, the ability for teleportation exists in the future.

Generally, the concept of teleportation refers to the ability of a person to mentally or physically, through some mystical still or, more often, via specialized machinery, break down their physical body and create a replica of that structure at another point in spacetime.

Of course this is borderline pseudoscience, but my question refers to actual biological repercussions of this concept.

Let's say in the example a computer identifies and analyzes the person in question and determines the exact properties, position, orientation, state, etc of each atom or molecule in their body. It then releases a swarm of nanobots to pick up the atoms, fly them to a new location, and reassemble the structure. I know this would be a horribly complex and inefficient chore, but it is simple.

Once all the atoms are in place (lets say for sake of argument it takes a total of 1 second), what happens next? As a layperson with no understanding of biology I think that the body would stand for a moment and then liquefy or fall apart, as even though the molecules are in the same place, all organic bonds and processes were halted and can't simply just continue on.

Anyone have any ideas or opinions on this, I've been think about it alot lately but don't have the scientific understanding to really come up with anything.

H-how do I do calculations with errors

For example
a = 50s ± 2s
b = 12s ± 3s

I want to subtract b from a. What do?

>>7139319
imagine if you could "freeze time" like in the typical way where you freeze everything around you but you can still walk around and stuff. imagine you throw a ball then freeze time while its still in flight.

when you unfreeze time, is the ball gonna lose its momentum and just plummet straight down or is it gonna keep flying along the same arc?

my boss sent me this riddle in through e-mail. First one to get it correctly gets $50.

I know it's kinda not math related but still. Any Help? I'm Thinking Yoshi or DK

>>7139333

The momentum would be preserved, I suppose. I guess I'm just not very good at communicating my question.

While the physical structure would still be in place, are there intangible systems (flashing of neuron sequences, blood flowing, bonds between molecules, cellular interactions) in a living being that, once interrupted, would cause problems? Or would you just feel tingly for a moment and keep chugging away

>>7139335
It was DK

>>7139335
>kinda not math related

>>7139335
The culprit is lying, so we know that it can't be Yoshi or Peach (their negative answer claim another would also be the culprit).

Bowser claims it wasn't him, so if he lies it would be him. Because DK, Mario and Waluigi all have an "it was either A or B" answer, if all claim Bowser was the culprit then we have an answer. Waluigi does not make this claim, so it cannot be Bowser.

DK claims neither Mario or Waluigi did it (the only other two possible culprits), so he did it. Simultaniously, Mario and Waluigi claim that DK is one of their two picks, reinforcing our conclusion.

>>7139345
I think I understand why it is DK but just to show my method to someone gets to verify I got the idea. Basically you have to go to each person, assume they are the culprit and then compare it to the other characters to see if choosing that particular culprit makes the any other character's statement a lie. For example if I think Mario is the culprit, then the characters who are lying are Mario (as the culprit), DK, Peach, and Waluigi meaning Mario cannot be the culprit. The only selection which results in there being only one lie is by picking DK as the culprit. Is this the right or most effective way to solve the problem?

This book is bullshit right? I'm about 70% through and don't even want to entertain the last bit if I don't need to.

>>7137045
>>7137055
So in that pic earlier, if the hydrogen atom was perfectly isolated so that there was no influence of any other atoms or any photons, there would be no blue region, right? Because with no other influences, the electron cannot escape outside the red center region, making the probability of it being in the blue region 0.

>>7137056
Have they been captured yet?

>>7150000
nevermind, discovered it

>>7139399
>This book is bullshit right?

No. Krauss is trying to educate you on the bizarre nature of our spacetime.

>There is[a magnetic field outside a toroid-shaped coil with current flowing], you are referring to an infinite solenoid/toroid. It's just that it is a lot weaker outside since it it more spread out. Inside the toroid all the field lines come together making is a lot stronger.

How do I calculate it?

>>7140355
you'd have to simulate it

but there is another thing you can compute by had
you know how the windings wrap around the toroid and come back around? that can be considered a single current loop
how can you compute that? its component outside of the line that goes through the middle of it, it cannot be expressed with equations either, you'd need elliptical integrals.

basically if you want the actual B field of a real object, you HAVE to resort to numerical methods

Why do we say that y=x2 doesn't have an inverse function?

>>7140509
Depends on your domain. f(x) = x^2 from the reals to the reals does not have an inverse because it's not one to one.

So I'm trying to wrap my head around convergence of sequences in normed spaces.

Any above avarage mathematicians here that would fancy to help? I'd shoot you a few small questions.

>>7140512
On the level of Baby Rudin? I got an A in the class that used that textbook so I can do my best if that's what you mean.

>>7140510
Ok, so you're saying reals to reals, so that means that I don't include negative x values in my domain , correct?
But what if I do have negative values in my domain? Does it have an inverse function then?
Also, thanks for helping out.

>>7140519
Well, I'll shoot you the question and you can do your best. Much appreciated for any attempt.

I've understood that all convergent series are chauchy series, but how would one go about to calculate the sum of such an infinite sequence? I.e a sequence (x_k)(k=1 to +inf) that converges to y.

>>7140509
the real vs imaginary argument does really not make sense
the main reason it has no inverse function is that if you had y=4 and wanted to find x, you wouldn't know if you should have x=-2 or x=+2
but in these cases (at least engineers and physicist) just pick a convention and go with it

>>7140520
Reals to reals includes negative x values in the domain, the entire real number line is from negative infinity to infinity. If we were restricting the domain to positive values, then it has an inverse, because f would then be one to one; this inverse would be square root of y = x, and it would be from positive reals to positive reals.

>>7140521
Sum of an infinite sequence? As in a series? If you're summing a sequence then if the sequence converges to a finite value greater than 0 then the series will diverge because you're adding a fixed number infinitely many times. If you mean calculating the limit of a sequence than that's usually quite difficult unless we know a bit more than usual about the sequence. If it's a monotonic bounded sequence than usually we can find its limit by looking for its least upper / lower bound, a trivial example of this would be 1 + (1/n). If it's a recursive sequence, say s_n+1 = sn(1 - 1 / s_n-1) then we know that sn, s_n-1, s_n+1 all have the same limit, so lim sn = lim sn (1 - 1 / lim sn) and then just using algebra we manipulate the fixed value "lim sn" to find the it in concrete terms.

>>7140525
Would it be correct to say this: A function does not have an inverse, if from the output it is impossible to determine the the input.

>>7140536
A function needs to be one-to-one to have an inverse.

f(x)=f(y) implies x=y

>>7140536
if you are asking this question for a math class, don't take my answers seriously because mathematicians are lyin and gettin me pissed

but, i would say so. there was something called vertical line test, horizontal line test
if different x values give the same y value, it does not have an inverse (for sure)
for something to BE a function and HAVE an inverse, it should either always decrease, or always increase

>>7140541
>for something to BE a function and HAVE an inverse, it should either always decrease, or always increase
assuming the function is a nice function (continuous)

>>7135708
Is there a way, for m positive integer fixed, to find all the integers n positive such that
n^(n+k*m) ≡ n mod m for every k>=0 integer
?
(not homework, it is a problem I made up myself, which is the main reason why im starting to think it's not possible (without bruteforcing)

>>7140535
A classmate said that one could use the formula

(1/N)sum(k=1 to N)x_k --> y when N-> inf for the converging sequence I mentioned above ((x_k)(k=1 to inf) that converges to y).

But I'll be damned why that works and neither does he.

A blackhole housing our own universe at another point in time is basically the concept of a wormhole, right?

>>7140555
its all a pseudo science bullshit
some dude's brain masturbation
it is a waste of time to think about them

>>7140551
Seems like you're just taking the average of all the times in the sequence. So as N goes to infinity, your sequence gets very close to the limit value, and you have many terms close to y, (infinitely many) which outweigh the initial x_1, x_2, which may not be very close to y. So as N goes to infinity the average tends towards y.

>>7140558
But they make TV shows about them.
How is that pseudo-science?

How do I into topology? Also, I would like to read about higher mathematics (beyond differential equations and vector calculus) that have applications to mechanical engineering!

Thanks in advance based anons.

>>7140563
yea, that seems reasonable enough. I got as far as to understand that the 1/N is about something that avarages.

Pic related is my problem basically. If the first part holds, then apparently the second part holds as well. Extremly useful, but what's the proof?

You don't happen to have any kind of more formal evidence?

>>7135708
Pauli Exclusion Principle, how does it work?

Yes, two half-spin particles can't occupy the same place, but why? What prevents this from happening? Why does my mum have so much mass?

>>7140569
I'm doing topology right now as a part of a course. It's pretty wierd and got tons of definitons to keep track of, but if you want to get into it I'd recomend you to do some functional analysis and intermediate level math first. Advanced calculus and algebra would also greatly help you.

how can I isolate y in x=y^2-4y

>>7140574
That's an exercise in Rudin actually if I remember correctly, but only in the case where x_k is increasing.

If x_k is increasing, then x_k is always less than or equal to y, and so 1/N sum x_k from 1 to N is always less than or equal to 1/N sum y from 1 to N which is y.

>>7140587
x+4=y^2-4y+4
x+4=(y-2)^2
you might be given a restriction on where y is
so it is
+-sqrt(x+4)+2=y

>>7140597
Fair enough, I understand that and I can buy that. But is it "trivial" that the first sum goes to y when you add up infinite Ns?

And would it affect the problem if the space was normed linear?

>>7140597
A follow up question would also be;
Even if the sum is equal or less than y, why would it add up to y?

>>7140650
You'd have to prove that for any number y - epsilon, there exists N such that 1/N sum from 1 to N of x_k is greater than y - epsilon, which is reasonably possible depending on the complexity of your sequence.

>>7140656
But this is just A random sequence from 1 to infinity (top of picture at >>7140574), surely there must be some general way to prove it?

>>7140667
http://math.stackexchange.com/questions/248116/arithmetic-mean-of-a-sequence-converges

>>7140686
yea thanks, thats the one.

But that is the "a" in |a_n - a|?
Is it an arbitrary a? Or the a that the sequence converges to?

Suppose it was equally possible, would sending New Horizons to Eris instead of Pluto be more scientifically interesting?

>Smell.
What exactly is smell and where does it come from? So I have a single copper atom, it has no smell. Is that true or is it just that one atom is simply too small? Then I take a trillion copper atoms and now I have a block of copper, and it has a metallic smell to it. If the block has a smell, shouldn't single atoms have smell too?

Is Virginia Tech a meme school?

>>7140799
smell comes from small particles being carried by the air into our noses where they land on cells with sophisticated chemical receptors. we can only detect smells if enough particles of a given type end up in the nose; there is a detection threshold.

the sharp "metallic" smell of metals, however, isn't actually from the metal. rather, sweat and body oil react with minor constituents of metal objects, and we associate the smell with the metal we just touched.
>http://www.nature.com/news/2006/061023/full/news061023-7.html

Guys, what does Rf stand for in chromatography? I was in biology class today and teacher asked this question. I said 'retardation factor' and I was struck down with an iron sword and he said the answer was 'relative front'. Help?

>>7140935
>what does Rf stand for in chromatography
>he said the answer was 'relative front'
Not only is the answer in your post, it's something you could find out in about 10 seconds with Google.
BTW, 'retardation factor' and 'relative front' both mean the same thing: (distance an analyte has traveled)/(distance the solvent has traveled)

>>7140953
Ok. I did try google though and only got retardation factor. I thought maybe the term 'relative front' was only used in biology

If the curl of some object is zero does it mean that the object is not spinning/rotating?

>>7141193
haha, is this serious?
no, that has absolutely nothing to do with it, well does have something to do with it i guess

lets say you have a blender and it is spinning
nothing is going in, or out
that blender has divergence zero, but has some curl

lets say you have a blender which is stopped, and you add fluid into it
it has zero curl but has some divergence

UNLESS the vector field you are talking about is a vector field of velocities, "spinning" has nothing to do with it

divergence makes you find the source
curl makes you find how much of the "thing" closes up on itself

and i'll throw in something else also
gradient makes you find the change
when you take divergence of gradient (laplacian), you find the *source of change*
for example electric charge causes change in Potential (volts)
laplacian of potential is charge (divided by a constant)

Let T: P2 -> P2 be the linear transformation definied by T(P(x)) = xp'(x).
a) Which of the following polynomials are in ker(t)? i) 2, ii) x^2, iii) 1 - x
b) Which of the polynomails in part a) are in range of T
c) describe ker(T) and range(T)

I'm so miserably lost on this section it is almost humorous. Anyone tell me what the fug I'm doing?

Started out by saying p(x) = a + bx + cx^2, sp xp'(x) = bx + 2cx^2, but this is far as I've gotten and I don't really know how to solve it. (or any of these problems for that matter)

advice would be appreciated, and better resources than my math book would also be appreciated.

>>7135708
How much is my poor sleep schedule impeding my performance in /sci/?

could someone help me with these two babby's first mechanics class questions?

for the first, I don't know how to calculate the speed at which it collides and for the second I can get the time taken right, but keep getting the wrong answer for the distance.

>>7141820
the thing will stop in 5.4/1.25=4.32 seconds
it will have traveled 5.4*4.32/2=11.664 meters before stopping
it will have collided

an intuitive way to find the velocity is vi is initial vf is final
t=10/( (vi+vf) / 2 )
( (vi+vf) / 2 ) is the average speed
vf=vi - 1.25 * t final speed is initial minus a * t
solve for vf

a mathematical way of solving would be, since you already have the distance formula down
(x: position v: velocity a:accel t: time)
x=x_initial+v*t+1/2*a*t^2
x= - 10 + 5.4 * t + 1/2 * 1.25 * t^2
time of crash is t when x=0
velocity of crash is for dx/dt when x=0

try the second one yourself, with your new found knowledge

>>7141945
this is the solution, how do we get K=2.2 ?
I tried it on matlab, it really is the fastest step response, however when I draw the root locus, the K value that makes the double rooth is 0.58
anyone with any understanding of this?

I was in a bait thread recently that involved the topic of buoyancy and now I'm wondering,

>Any body wholly or partially immersed in a fluid experiences an upthrust equal to, but opposite in sense to, the weight of the fluid displaced.

How could Archimedes prove this with tools and knowledge of the time? The fact that an object rarer than water will float on an equal volume of water while a denser one will sink makes it obvious to me now, but was it somehow obvious even before the principle was discovered or is there some clearer way of demonstrating this?

I know that I'm dim and poorly educated.

How do I determine how much energy(KWh) is output by an antenna?

>>7136845

thats a jizz bottle isnt it

>>7136936

I believe you only need one per year.

I currently have bad lower back pain. I've been taking an Ibuprofen roughly every six hours to alleviate the pain. I did so last night, and woke up a full ten hour later, my back pain quite diminished. I had to take another Ibuprofen two hours later as per normal.

So: can sleep and its relative lack of activity (compared to being awake and active) affect a medication's longevity?

>>7135708

I like chemistry but I also like being outside

How well would a degree in Environmental Chemistry fit with these?

is there any good video explaining how the curvature of space effect gravity or something?

>>7143196
>I like chemistry
Study chemistry
>I like being outside
Spend your free time outside

>>7135708

I just cut off a skin tag with my knife. It might sound weird but I could sort of 'taste' the metal, like when you have blood in your mouth and it tastes metallic. The skin tag was on my waist.

Could anybody explain this?

>>7143308

What happens when an unstoppable force meets an immovable object?

>>7143363
>What happens when an unstoppable force meets an immovable object?
the terms used are not well defined.

>>7135708
What breakthroughs made wireless charging practical? Are the coils now made of some superconducting alloy?

>>7136936
It's the 2008 version of their standard visual C++ library.

>>7135708
Is it okay to drink like one can of light American beer on Zoloft?

>>7135906
because they ARE smaller.

How were physics constants calculated? Like Planck's constant, Avogadro's constant, Boltzmann constant, the gas constant, etc.

They never really cover how these were derived and it just boggles my mind how these guys could pinpoint such microscopic numbers like this back in the 1800-1900s.

>>7135708
With the clear, irrefutable scientific evidence that the Shroud of Turin is a legitimate burial cloth of a man that fits the description of Jesus Christ, and all claims of it being a hoax being "debunked" and has within it an image made by no known scientific method, how are there not more scientists who believe in Jesus Christ?

https://www.youtube.com/watch?v=4G4sj8hUVaY

Your years of effort have paid off.

You've been developing a small, one man spaceship for the last 10 years. Finally it's complete and you have enough fuel to reach the ISS. You press the button and ZOOM, away you go. Your local federal government is probably freaking out about an unidentified missile showing up on their radar, and you just laugh your ass off on your way to space. You break through the atmosphere and become weightless. Observing the spherical roundness of the planet, you're awestruck by it's beauty. Entering a low orbit, your auxiliary fuel tanks break away and will disintegrate upon reentry. You're in space. Finally. You make your approach to the ISS and dock at the JEM (Japanese Experiment Module). The ISS crew isn't sure what to make of this, but given the go ahead from their superiors at ground control let you into the station. Your eyes meet all the crews eyes, and they wait for you to speak...

What are your words as the first person to privatize your own space trip?

>>7143759
NIGGERS

>>7143759
AYY LMAO

Would it be possible to construct a coil gun with a coil that started to spiral outwards/inwards (like in the picture) about halfway down the barrel? Would the projectile experience more/less acceleration when passing through a wider barrel?

>>7143759
1. I take out an envelope with my resume and a general NASA application form. "I'm here about the job interview."

2. Take out check list, check "visit ISS" off list turn around and leave without a word.

>>7143791
if you look carefully at the coil in the image, you'd see that the two halves of the coil twist at the top and come back down with opposite winding directions. This means they will cancel each other.

if your coil was wound as in this picture, it is not so easy to determine
my intuition says it'd be not as good as a solenoid wound as tightly as possible with the narrowest passage
my intuition says it'd be a bad idea

i am curious, i'll try to think more about it
one would need to make a simulation to be sure, I can't bother though

>>7143961
also, i should mention, the only reason there is a doubt that the helical might have any positive effect at all is if it makes it unnecessary to deactivate the coil once it passes halfway through

I might numerically evaluate the B field along its axis in the next few days

>>7143656
Ask your physician or pharmacist. Do not drink until you find out.

>>7141789
A lot more than you could possibly imagine.

How competitive are math phd programs?

>>7144466
If tons of hard work means competitive then very yes. The good part about it is if you want to back out of it you can get a master's from your completed coursework and leave for teaching or industry.

>>7144482
I mean getting into them, I'm not worried about the work I'll have to do once I get in.

>>7141949
The roots furthest away from the imaginary axis of the root locus will have the fastest response, I'm not sure what you mean by "double rooth", but having 2 imaginary roots on the root locus implies oscillatory (the further away from the real axis the more oscillatory) behaviour but you can have a single real root that could potentially still have a faster response.

>>7142524
The "tools and knowledge of the time" included ways to measure weight and force, read up on Aristotelian physics, even before his time Egyptians had scales.

>>7142541
You can measure the current, voltage and induction. If the output functions are constant you can find the average power output by taking the integral of power of one time period

<span class="math">\frac{1}{T} \int_0^T p(t) dt[/spoiler]

where p(t) = v(t) i(t)

You can solve this in the time domain, but it's easier to convert it to the frequency domain first.

Once you've found p(t) you know the power consumption in Watt, now multiply by the total time the antenna is outputting for the total energy in kWh.

If the output of the antenna is not constant, you will need to calculate the power consumption for arbitrary discreet time elements p(delta t) = v(delta t) * i(delta t) and energy equal to p(delta t) * delta t. The delta t sampling period must be chosen as such that it is more than twice the original frequency (google Nquist frequency), but choosing it arbitrarily small should still give you a decent estimate depending on the signal form and available filtration.

>>7144488
Even though I am where you are asking about, I don't really know. My whole post-secondary life I've been wondering why schools have been letting me attend them. I'm a lousy student except I pass hard math classes and get good grades on standardized tests.

Some math phd programs are focused on producing teachers, such as professors at two-year universities, rather than researchers. Those should be less selective. But you will have to know your stuff well enough to be cheap labor for them as a teaching assistant unless you are rich enough to pay tuition for another four years.

>>7142745
Not really, your liver doesn't stop working during sleep and if anything the half life of any medication in your system would decrease. Do you know what's causing your back pain? You should probably go see a doctor, taking that much ibuprofen is really bad for you.

>>7144518
Thanks for the response. Are you on the teacher path or the researcher path?

>>7143196
Professionals don't really get to go outside much, at most you'll take samples as a student intern before it becomes too expensive for you to waste your time in the field.

>>7135864
DAG is a commonly used abbreviation.

>>7135708
Did the FOXP2 gene help us invent comprehensive language?

>>7143758
There's millions of nutjobs like JC that claim to be the messiah every fucking day.

>>7144523
The program I am at is a random state school. Though it seems rigorous I have no illusions about my ability to compete with people from elite programs for the very limited number of professorships at research universities. This particular program requires its students to work in both pure and applied mathematics, so I should some option for employment in industry should I complete.

How important is GPA when it comes to getting jobs in the engineering field?

>>7144745
It depends highly on your school and the employer, most companies are aware which engineering departments have high grade inflation and which do not. The usual safe bet is a GPA higher than 3.0 for most universities, at more traditionally graded universities for example in countries like the UK GPA basically becomes irrelevant and just getting your degree is enough to get you a job or acceptance into most grad schools.

Where GPA is important it is also only important for getting your first job, after that experience and publications become much more important. By your 2nd job you won't even be putting your gpa on your CV anymore unless you got a 4.0 at a really good university no one will care. Good students do not always make good engineers.

>>7143693
>How were physics constants calculated?
That obviously depends on the constant. Some of them are derived mathematically from other constants, other ones are derived experimentally. You can easily find these yourself on Wikipedia. Usually there are multiple ways of arriving at the same result and scientists are always on the lookout for new types of experiments that can get even more accurate results for any specific experimental constant.

>They never really cover how these were derived
If that's the case, you are using a shitty textbook imo. At the very least you should understand how the first person who discovered a constant was able to deduce (a first estimate of) it's value. I am personally a big fan of Giancoli so I would suggest you have a look at that. If I remember correctly it always mentions this sort of stuff.

>>7144951
>If that's the case, you are using a shitty textbook imo
noone has told me how any constant was every measured ever

>>7140935
IIRC, it's the distance that the frontline of your mobile fase has moved.

>>7144970
That's an absolute shame. You should really look into it. It's usually pretty interesting and it's very important not to think of science as plug-and-chug magic. Like I said, find out how the original scientist arrived at that value. Imagine yourself in his shoes try to follow his logic. You are going to discover really quick that it's never as complicated as it might seem at first to an outsider. Have fun!

I want to learn how to make a machine - like a blender and a sewing machine. That thrusts while rotating. Also, I want it USB and software enabled. I want to have externel controls as well.

What sort of things should I learn ?

-electronics
-?
-?
-?

I am in position of Solid Works. Will that help at all? Probably of design, but the other components too?

>>7145338

possession*
external*

Yes, it is a fuck toy.

>>7145338
>I want to learn how to make a machine
no one man can make a machine
you need many different specialties for even the simplest devices

>>7145338
For even a fairly simple system like a blender you would pretty much require:
-An understanding of mechanical design: tolerances, fitting, filleting, extrusion.
-Understanding of embedded systems, programmable logic
-Fundamentals of electrical networks, circuit components like resistors, transistors, capacitors, diodes.
-Signal processing and fourier analysis, control systems, closed-loop and PID controllers.
-Manafacturing processes, i.e. actually being able to build some sort of system. Soldering circuits, 3D-printing complicated plastic components, manually sawing or cutting out components, drilling, screwing, hammering, etc.
-Money and time

>>7144765
What about getting into a masters program? I want to pursue molecular biology in Germany, but my CGPA is going to be ~ 2.7 when I graduate. Does it help that my undergrad. major was mostly unrelated (biomed. eng.)?

>>7145346
>no one man can make a machine
this is what non-engineers actually believe.

>>7145338
Solidworks is a good start. it lets you model prototypes and make adjustments pretty rapidly. once you get used to it, its basically a really advanced virtual lego kit.

learn CNC and start hitting up machining forums. are you in college right now? if so, they probably have a machine shop in the mech E dept.

>>7145466

I'm a psych/math student.

I just want to learn how robotics/electronics and shit like that.

>>7145444

Thanks to trips of truth.

3D modeling/ printing. Np.

Suppose I could just start by modeling it in Maya/Solid Works. And then learn about circuits/eletronics as I go. Again, thanks.

Very determined to learn this stuff.

What is the best degree for getting into planetary science?

>>7145590
Depends.

There's a PhD student in my math department doing work on mathematically describing black holes.
But probably Physics.

>>7145590
Probably astrophysics, geology, or meteorology depending on what you mean by planetary science.

Is there any way to model a bouncing ball in real life, considering it eventually comes to rest? Everything i've seen is like a geometric series which never reaches zero.

mathbros!

ive been thinking about switching to mathematics as a major, (currently in forensics) because I very much enjoyed calc I and II as well as linear algebra. just a few questions:

-is this viable for a career down the road?
-just because I liked calc and linear algebra, will I like the more complex math down the road?

thanks!

>>7138214
There are exceptions. I got a SW engr job right out of collage with only a BS in math. And co workers have physics degrees. Depends on the company you apply for.

I don't care anymore

>>7145625

You haven't even begun to learn math, kiddo.

All ions are atoms, but not all atoms are ions right?
Obviously trivial, but my high school teacher used to go on about how ions weren't atoms, was she right?

>>7144511
but what makes antennas different(have more output) from open circuits?

>>7145767
>she
wrong, obviously

>>7145338
Other posts covered it in more detail.

Get a control engineering textbook. I suggest learning Python so you can build a cheap RaspPi controller.

>>7145456
Don't know about Germany, but in UK and US at least it's very easy to get into a pure science grad school if you graduate with an engineering degree. I understand that German engineering degrees are less theoretically orientated so I'm not sure.

I don't know why you would want to do biochem in grad-school, you probably covered everything in undergrad already, if you want good money in bio study Biochemical Engineering instead (involves a lot more reactor engineering and other Chemical Engineering principles). If you want to do biochem research you're already set to do that, just apply for internships at labs and try to get your final year undergrad research published.

>>7145466
>CNC
>mfw MechEs with their cutely outdated tech.

>>7145535
Ignore him, ask someone with a 3D printer to print your model for you then extrude a polymer to produce your "product".

>>7145609
Of course there is. Find the transient force balance (should be a simple linear ODE) then apply any estimate for the energy losses and find the transfer function and you'll see that <span class="math"> lim s -> \infty s*TF [/spoiler] is equal to ground level.

>Everything i've seen is like a geometric series which never reaches zero.
It should converge unless it's defined as perfectly elastic.

>>7145641
Just because your company calls you a Software Engineer, does not mean you're a software engineer. There are secret little clubhouses that you can't get into without a SoftE bachelors that lobbied years ago to protect the legal definition of the profession.

In any case many code monkey jobs are often wrongly labeled as SoftE.

I've met tons of Physicists who were hired into technologists jobs labeled "X engineering technologists" which becomes reduced to "X Enigineer" etc., they all think they're working as real engineers and somehow don't realize they earn half the salary of a professional engineer.

The best place for Physics who want an actual STEM career remains as a proper R&D Physicist, similarly to math.

>>7146314
>lims−inf
the problem is, you don't have to wait until infinity i n real life

>>7146327
lim s−infty does not mean infinite, it means as you approach infinite, there will be a finite time after which the motion of the ball approaches zero until the vibrations cease to have meaningfully large numbers.

You were explained how Zeno's paradox works when you took calc I so you should be able to understand why it's the same as zero. Nothing in science or engineering would work if it is not.

>>7135919
>this guy

>>7135906
Because more of the light that's bouncing off of it is going in a direction away from your eyes. Your brain gets fewer 'pixels' with which to construct an image. When you combine the effect from both eyes, the brain interprets that smallness as further away.

>>7145625
Calc and Applied Lin Alg are nothing like higher level mathematics
Take Real Analysis, and then decide.

>>7146303
I wanna get into tissue engineering and I'm not looking for top paying jobs. I want to be a research scientist. Tissue engineering is very interesting and has massive potential.

>>7135708
if I liked working though Spivak's Calculus, will I enjoy pic related?

Could a shadow sweep across a surface at velocities greater than c?

Guys I need to explain this to my cousin but I haven't done any math since Calculus 1 five years ago.

It's probably very simple but I'm not seeing it, we've done like 15 of these in the past half hour and they all went OK.

Pls what am I not getting/forgetting?

How do you do a standard before/after bar graph when you have values that aren't 'absolute'? I don't really know the terminology, but I've got before/after values that only make sense in relation to each other.
i.e. 0.1mV and 0.7mv and the next subject has 300mV and 1200mv etc.

I'm stumped, because I've never had to deal with mismatching data before

>>7146556
I own that one and used it a bit as an undergrad. The concise presentation is very enlightening. But it also makes it a particularly challenging presentation of undergraduate abstract algebra. I love it, but the presentation is tricky to understand and abstract algebra as a subject is really tricky. There is a big gap in difficulty between calculus and abstract algebra.
>>7146576
You betcha.

>>7146556
It will be on a wholly different level of difficulty than Spivak, but if you could do all the exercises in Spivak, I'd say go ahead and take a shot at Artin.

>>7146576
I thought shadows can't have a velocity since they are simple an absence of light

>>7146576
>Could a shadow sweep across a surface at velocities greater than c?
light it self can sweep across a surface at velocities greater than c
it is a single photon which cannot travel faster than c

>>7146582
the ((a + b) + c) term on the top is exactly the same as the ((a + c) + b) term in the denominator, of course assuming additive commutativity. You can divide it out of the top and bottom to get your answer

>>7146619
So if you had a lighthouse rotating near c, the light it projects, onto say a mountain, would look like a broken up line?

>>7146622
My god, it's so fucking easy, it's like the easiest one of them all...

Thanks anon, I hate it how soft my brain has become.

>>7146633
no
there wouldnt be anythin magical about it
there is no speed limit
the speed limit can only be the engineering considerations for making the lighthouse spin

>>7146662
>>7146662
> implying

>>7146500
Sounds vague, just do materials science instead, you'll employable in that industry.

>>7146679
*Than biochem I mean

Biochem is undergrad stuff, you need to study the techniques and the science offered in post grad mat sci courses which is more closely related to physics that the chemistry you'll be doing in biochem.

>>7146679
>>7146682
Tissue engineering/stem cell research. I'm not sure, but it involves a lot of lab work. I'm thinking a year or so of lab training after I graduate will help.

The last thread seems to have reached it's bump limit, so I'll dump the question I had here in hopes that I've finally got it.

I've done the actual question in pic related, I just wanted to tidy this up.

Here's where I got to in the last thread

"At all points, the sum of the contact force (R) and the weight (W) will be the centripetal force (C), which I'll assume to be constant.

At A, R+W=C, however R must equal 0 because I see not way that there can be a normal contact force at A (the sock isn't moving towards the container at this point).

At B, I haven't got a fucking clue, R must equal 0 because I see not way that there can be a normal contact force at B (the sock isn't moving towards the container at this point), however the weight is at a right angle to the centripetal force, so it's irrelevant, somehow 0+0=C, which is bullshit.

It follows that I cannot assume that the centripetal force is constant, therefore it's beyond the scope of my course.

Therefore all that remains to satisfy is my own curiosity as I've already answered the actual question.

What the fuck is happening at B?

Oh, and am I right to say that there's no contact force at A?"

If anyone wants to read the details from where it all kicked off, start here >>7144698

>>7146702
>The last thread seems to have reached it's bump limit

>>7146702
>>7146705
highschooler get out
REEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEE

>>7146705
Oh fuck... I'm too used to have limits over 500.

>>7146702
greatest at C, because of gravity
weakest at A, because of gravity
just so you'll shut up

>>7146711
>I've done the actual question in pic related, I just wanted to tidy this up.

The main things I'm asking are whether or not it's 0 at A and what the fuck is happening at B, the rest I understand.

>>7146693
Yes, but "lab work" is for lab technicians, if you actually want to be researcher in tissue engineering you'll need a PhD in mat sci or similar, maybe biochem but it's far less useful than mat sci and I don't see them getting hired as often because they aren't as good at modelling as physics/engineering --> mat sci or other post grad.

The most experienced PhD runs the research team. The lab techs, who usually have a B chemistry or similar degree or even a technical diploma do not get to do any real research; they run monotonous tasks directed by the lead scientist in the group. The latter group does not "advance" in their careers, if you're a lab tech you stay a lab tech until you die. This is as opposed to real researchers who mostly work in the dry labs/offices and model/interpret results and eventually lead their own research team.

Scientists and engineers aren't employed to do lab work, they are employed to design the experiments, you are already over qualified to do grunt lab work.

>I'm thinking a year or so of lab training after I graduate will help.
Would be the worst mistake of your career.


I suggest you take a summer internship at research lab to find out what R&D actually is before you fuck up your life based on some vague idea of what you want to do because you read a buzzword filled pop sci article.

Does the total electric flux in a gaussian surface remain the same regardless of radius?

>>7146741
as long as the total charge inside is the same, the *total* flux through ANY arbitrary shape will be the same, no matter the size or shape
if the charge inside is not a spherical, spherical shell, point charge and and gaussian surface is not a spherical one, the total flux will not be uniform

If the air is only 20% oxygen, could you survive in a room that had everything taken out of the air except the oxygen? Or a room filled with 100% oxygen, but the air pressure is only 1/5 of the usual amount?

>>7147146
Low pressure pure oxygen is fine. In fact space suits use pure oxygen below 0.3 atm for flexibility.

>>7147146
I have no basis but i'll say no

>>7147160
but its not NATURAL
you don't want to subject your body to UNNATURAL CHEMICALS which is pure oxygen
this fuckin age.. everyone is a lab grown baby, this isn't how a human should live

>>7147160
Atmospheric pressure pure oxygen is bad in various ways though.
http://en.wikipedia.org/wiki/Oxygen_toxicity

>>7147160
Thanks

>>7147168
This isn't relevant, true, or controversial. Try again.

>>7135708
You're standing in front of the LHC preparing to fire it.

You had five samples of five elements; Tc, Md, Np, At, Lr.

Which one did you use as the target, which one did you use as the bullet, and why?

Highest level of math I "know" is algebra, what books would you recommend to work my way towards calculus?

>>7146726
How would materials science help in tissue engineering?

Why do meteors always land in craters?

>>7147509
Magnets.

>>7147509
The bottom part of a crater is closer to the center of the earth, so gravity is stronger there.

>>7147509
because the flow of aether is the greatest there

>>7147509
It's more that by definition they need to land in a crater. If they don't land in a crater we just call them a rock.

>>7147509
Ancient cultures like the egyptians knew exactly where meteorites would land in the following millennia. They dug huge holes to prevent coming generations from building and living there.

Guise? Answers please? >>7147332

Please respond. People responding to me on 4chan is the only human contact I have. My life, my very SANITY, is on the line here guys.

>>7147541
what sort of question is that
who asked you that question
did you come up with the theoretical yourself

>>7147545
Its simply an opinion question, there is no right or wrong answer per se. I came up with it myself and I asked it myself.

>>7147549
i doubt anyone would be answer that question

>>7147551
Are you sure you're looking at the right post? My question was >>7147332

>>7147555
yes, no one can answer such an arbitrary question

>>7147562
You sure you couldn't just say "I picked (element 1) and (element 2), here is why"?

That seems easy to me.

>>7147571
Not him, but I also don't understand the point of your question at all and it feels unethical for me to answer it and pretend it has anything to do with science.

>>7148663
probably someone from b