Stupid questions thread

[Anonymous No.6931085]

New stupid questions thread because old one is at page 8.

Only sensible questions please.

[Anonymous No.6931110]

>>6931085
How can a question be sensible yet stupid at the same time?

[Anonymous No.6931115]

Need to calculate double integral in polar coordinates. The space is between x^2+y^2=4y and y>=2
x=rcos(theta)
y=rsin(theta)

How do I find theta? At first I wrote theta is between 0 and pi but it was wrong. The next time I wrote theta is between pi/2 and 3pi/2 but it's also wrong. Can anyone help me?

[Anonymous No.6931131]

>>6931115
Pic related. I don't understand why thete isn't between pi/2 and 3pi/2

[Anonymous No.6931134]

>>6931131
>>6931115
Now I got it. pi/4 and 3pi/4. Fuck how didn't I see it

[Anonymous No.6931137]

>>6931085
>>6931085
/sci, I've always had problems with ratios. They didn't seem rational to me and I've always tried to dodge them as much as I could. Always knew they would come back and bite me in the fucking butt, but never seemed to be in the mood to get into those irrational concepts that could be replaced with fractions and words.

Nonetheless, young brother showed me this question from his maths textbook:
>If x:18=8:x, calculate the positive value of y
I spent a good dozen minutes on it trying to figure it out in the beginning, gave up, and then went to Wolfram. Got http://www.wolframalpha.com/input/?i=x%3A18%3D8%3Ax, which seemed to work because:
>x/18=8/x
>x^2/18=8
>x^2=144
>x=12
Everything was smooth and shit, but then I remembered that n:m=n/(m+n). Tried Wolfram again but I got http://www.wolframalpha.com/input/?i=x%2F%2818%2Bx%29%3D8%2F%288%2Bx%29, which is the same answer. But, by plugging the values into x/(18+x)=8/(8+x) I get:
>12/30=8/20
>2/5=2/5
Which is not the same answer as x/18=8/x. I tried Wolfram again and got http://www.wolframalpha.com/input/?i=%28x%3A18%29%3Dx%2F%2818%2Bx%29, which is (x:18)=/=x/(18+x) for x >< 0.

I tried, /sci/. I really tried. But I just don't get ratios. I have completely alienated myself from them before but now I just cannot escape from the fact I do not understand bullshit 6th and 7th graders understand. Help me, /sci/. Please, for the love of whichever deity you believe or don't believe in, explain ratios to me and tell me what the fuck is the purpose of them. And will I ever gonna need this in higher level Physics/Mathematics?

[Anonymous No.6931142]

>>6931137
>n/(m+n)
But that's not true.

[Anonymous No.6931152]

Why cant we just plant treas on Mars and make a habitable atmosphere? I mean its full of CO2

[Anonymous No.6931154]

>>6931152
Plants need water and oxygen

[Anonymous No.6931158]

>>6931154
We could make an automatic sprinkling system. As for oxygen, wont the tree make himself some?

[Anonymous No.6931160]

>>6931158
>We could make an automatic sprinkling system
Where would you get the water from?

[Anonymous No.6931164]

>>6931152

no oxygen
too cold
no nutrients

[Anonymous No.6931165]

>>6931158
I'm not biology expert but I remember that even though trees produce oxygen, they need it for survival. If there is no initial oxygen, trees would instanteniously die.

[Anonymous No.6931166]

What the fuck IS conventional current?

If it's wrong, why do textbooks still acknowledge it and electron flow at the same time?

[Anonymous No.6931198]

Question level retard here.
What if we put air between two press and we start to compress this air. I imagine we can't "destroy" this air, so there are a point where the press can't compress anymore ?

[Anonymous No.6931201]

>>6931198
If there is no way for the air to leave, then yes.

[Anonymous No.6931202]

>>6931198
Explosion

[Anonymous No.6931203]

>>6931198
The sides will probably break from all the preasure

[Anonymous No.6931214]

>>6931198
What explicitely happens is highly dependent on the gas, but in general most gasses will liqify or solidify if you just put enough pressure into them.

[Anonymous No.6931221]

What is the difference of radiation and raidoactivity?
How can radio signals go through walls but are stopped by metal wire/faraday cage?

[Anonymous No.6931228]

I don't understand radiowaves. How is it possible that someone found out about them? How is it possible to transmit them? It just seems unreal for me, how could anyone discover radiowaves in 19 century. What were they looking for when they discovered them?

[Anonymous No.6931235]

>>6931228
Also I don't understand how can you transmit information by using electricity or waves. How does the electricity know what information you are giving her? (I know sounds stupid)

[Anonymous No.6931244]

>>6931221
Radiation is just a general term for electormagnetic waves. Electromagnetic radiation can come in different wavelenghts (see picture) or frequencies (frequency = 1/Period = speed of light/wavelength), a small part of which makes up the optic spectrum (i.e light, or radiation that you can see).

Radiation with high frequencies (and therefor short wavelenghts) contain more energy than low frequencies, since they "jiggle" around faster.

Lower frequencies than the optical spectrum are heat radiation, and then radiation to transmit FM and AM signals.
Higher frequencies are used for X-ray, and then comes the very high gamma radiation that you see with radioactive decay or fusion processes.

Now for radioactivity:
Radioactivity is just a term that describes _materials_, i.e atoms that decay into more stable (lower engery) levels, and therefore give away energy and/or particles (alpha/beta decay). There's also the case where an atom gets into an excited state (with higher energy), and drops back to its normal state where it gives off the energy by EM radiation (gamma decay). This energy is usually in the "gamma" part of the spectrum, very high Energy EM radiation, and can therefor do a lot of harm to living things.


An important distinction: Radiation itself never is "radioactive" (which really is just pseudo-greek for "emitts radiation"). Atoms are radioactive, because they can send out radiation.

[Anonymous No.6931252]

>>6931235
To transmit information via EM-waves you have to modulate the wave.
There usually are two kinds of modulations:
Amplitude Modulated (AM):
You increase the amplitude at certain parts (imagine e.g high amplitude wavefronts are 1s, and low amplitude wavefronts are 0s).

Frequency Modulated (FM):
You change the frequency of your wave.
Frequency modulat

[Anonymous No.6931262]

why is a system of linear equations solveable if det != 0, but when calculating eigenvalues det(A-Ex)=0?

[Anonymous No.6931271]

>>6931252
But how do you put information in wave?

[Anonymous No.6931274]

>>6931271
You put post it notes on the wavefront

[Anonymous No.6931278]

>>6931274
How?

[Anonymous No.6931282]

>>6931262
Why do you think they should be the same?

[Anonymous No.6931283]

what is temperature of vacuum?

[Anonymous No.6931285]

>>6931283
there is no temperature

[Anonymous No.6931287]

>>6931271
By defining what certain characteristics of the wave are. As I said above: If you say 1s are high amplitudes and 0s are low amplitudes, (and if the guy on the receiving end knows this), you can for example send
>low high low low low low low high
which would translate to
>01000001
which is an A on the ASCII table. Of course in practical terms it probably won't be executed that way, but that should give you an idea of how information is transmitted

[Anonymous No.6931291]

>>6931287
Thanks

[Anonymous No.6931294]

>>6931287
One more thing though - how can sound be transmitted through waves?

[Anonymous No.6931298]

>>6931294
what waves do you mean, sound or electromagnetic waves?

[Anonymous No.6931299]

>>6931298
electromagnetic

[Anonymous No.6931300]

>>6931137
Hahaahaha all this trouble for a such a trivial mistake i know you understand. As some1 pointed out it is not true that n/m=n/(n+m) i mean why would this be true haha?

[Anonymous No.6931304]

>>6931282
if you want to calculate the eigenvalues you sort of have a system of linear equations, dont you?
i mean if i have the equations Ax=0 with x!=0 and det A!=0 its solveable.
if i have (A-Ex)v=0 with v!=0 then i have to calculate det(A-Ex)=0, which doesnt make a whole lot of sense to me right now. i did a linear algebra class a few years ago, but i kind of forgot the reasoning behind the whole process

[Anonymous No.6931311]

>>6931085
What I don't really understand, is why our atmosphere, especiallyall the air around us spins along with earth.
I mean I understand why we move along with it,(due ti gravity right?) , but I don't see, why the oxygen molecules etc. are also.

Can someone please explain?
I know it's pretty stupid, but that's what the post is for. :)

[Anonymous No.6931312]

>>6931085
What are some really good books, strong in vocabulary and concepts for basic biology and chemistry? Also books that actually have testing material or coursework included would be grand.

[Anonymous No.6931314]

>>6931311
friction? i dont really understand your question, whats your problem?

[Anonymous No.6931318]

>>6931299
basically you can combine all the frequencies of the sound wave which have different strengths into one wave which, when you play it sounds like the original sound
cont.

[Anonymous No.6931319]

>>6931314
Why do the molecules move along with earth's surface just like us, when they have such a small mass?

[Anonymous No.6931324]

If you stuck a bunch of chloroplasts in an animal cell, would they photosynthesize?

Could we engineer bacteria that would survive on mars?

[Anonymous No.6931332]

>>6931311
I guess you could say is the conservation of the momentum when it all started. Think that we are not just only spinning but also all the solar system is moving with a lineal speed from the point of reference of the big bang

While such things like air spin around the earth they have two forces on them: gravity and centripetal force.

Sorry for my bad english

[Anonymous No.6931333]

>>6931318
with this wave (the signal) you now modulate the wave through which you want to transmit the information

[Anonymous No.6931348]

>>6931319
Because there is friction between the ground and the atmosphere, so the air molecules gain momentum and thus they begin to move.

[Anonymous No.6931353]

>>6931324
Need water and oxygen

How much volume of air do we need to fill the atmosphere of Mars?

[Anonymous No.6931426]

>>6931348
What? Things don't need force to move, the only need force to change direction or go faster in the same direction.

[Anonymous No.6931577]

What is the current prevailing theory of reality?

From what I recall there as talk of computer simulations, multi-verses, but I really don't understand what's what in terms of legitimacy or what the implications are outside of nothing really is as significant as thought.

[Anonymous No.6931589]

Say you are floating along through space in a closed box with no windows, moving towards a large mass, and you execute a trajectory like the one in the pic. Would you be able to tell you are accellerating from inside the box? My gut says you have to be able to tell you are accellerating, but when I picture this scenario, I feel like you would just feel like you were in freefall the whole time.

[Anonymous No.6931592]

>>6931577
if you want popsci-level explanations there is none, there's a wide range of interpretations that are valid. it's science. if you wanna learn it, learn it. if you want someone to digest and tell you some fun words so you can feel safe with them, then any will do.

[Anonymous No.6931599]

What happens to the dx term after you take the anti derivative of an indefinite integral?

[Anonymous No.6931609]

>>6931589
Nope. The box around accelerates at exactly the same speed, so you'd just be in freefall.

[Anonymous No.6931638]

>>6931592

Point taken.

[Anonymous No.6931639]

Does anyone know of any good introductory meteorology textbooks? Ideally with a bit of maths behind them.

[lee No.6931649]

>inb4 homework hurr durr

It's no homework - pic related - is just a couple of exercises that I want to understand in order to prepare myself.

Unfortunately I don't understand shit and I know here are a bunch of guys who are pretty /fit/ in maths.

How do I solve pic related?

[Anonymous No.6931670]

>>6931649
Alles trivial, man muss bloß ein bischen nachdenken.

[Anonymous No.6931673]

>>6931670
Ich weiß, nur das Ding ist, dass ich im Krankenhaus war und nicht verstehe, wie was gemacht werden soll.

Die Methodik ist jedoch wichtig.

Kannst du mir erläutern, welche Methoden/Vorgehensweisen dahinter sind?

[Anonymous No.6931681]

>>6931577

>>6931608
The only correct answer. All glory to timecube.

[Anonymous No.6931717]

Why do objects with more mass weigh more? I mean, if you drop a bowling ball and feather in a vacuum they'd both hit the ground at the same time. So Earth must be pulling both objects towards it with the same amount of force. But then if I'm holding the bowling ball in one hand and the feather in the other, the bowling ball feels like it's being pulled with much more force.

I just don't understand.

[Anonymous No.6931730]

>>6931673
Schau dir mal die 1a zum Beispiel. Wenn man ein bischen Werte einsetzt sieht man den Zusammenhang

a_n > 1/2 genau dann wenn a_n<1

Dann kann man sich ja schonmal raussuchen welche von den beiden man zeigt. a_n < 1 scheint ja ziemlich einfach zu sein (versuchs z.B mal mit Vollständiger Induktion).

Es steckt hier nicht wirklich irgendeine Methodik dahinter, es ist im Grunde nur rumspielen mit den Werten.

[Anonymous No.6931749]

>>6931717
>if you drop a bowling ball and feather in a vacuum they'd both hit the ground at the same time. So Earth must be pulling both objects towards it with the same amount of force.

Nope. F=ma <=> a=F/m. The Forces aren't the same, it's just that the masses are different and cancel out the difference.

This is, by the way, not a coincidence. The formula for gravitational pull is F=G*Mm/r^2 , where G is a constant, M the mass of earth, the mass of the object and r the distance between their centers. So obviously F/m = (GMm/r^2)/ m=GM/r^2 is constant and the same for every object, however the actual forces aren't.

[Anonymous No.6931777]

>>6931730
Ich probier's mal. Kannst du mir nen Tipp zu den Taufgaben geben? Bist du im IRC oder so?

Sonst sitze ich halte echt noch die ganze verfickte Nacht daran - nicht das ich damit nicht gerechnet habe - aber danke schonmal.

[Anonymous No.6931803]

>>6931777
*teilaufgaben

[Anonymous No.6931823]

>>6931777
b) Benutze den Hinweis und ziehe die Formeln zusammen. Das kannst du dann zu nem Term der art 1/x * |a_(n-1) - a_n)| zusammenführen. Dann kannst du mittels a) 1/x abschätzen.

c)hab ich nicht durchgerechnet, würde aber versuchen mit vollständiger Induktion ranzugehen. Das das Ding ne Cauchyfolge ist ist (falls du den Zusammenhang bewiesen hast) ziemlich einfach ersichtlich (schau dir im Zweifelsfall einfach die Definition einer Cauchyfolge nochmal an).

d) Ist ehrlich gesagt nicht trivial, aber "grenzwert rekursiver folgen" googeln sollte weiterhelfen (eventuell ist auch was in deinem Lehrbuch drin, falls du eins hast).

3a) Verrat ich nicht :)
3b) "Majoritätskriterium"
3c) ?

Für die Analysis 1 ist neben den Standardlehrbüchern wie Heuer etc (einfach in die Literturliste des Profs schauen, oder nachfragen) vor allem "Tutorium Analysis 1 und Lineare Algebra 1" von Florian Modler und Martin Kreh hilfreich. Für die Algebra 1 "Lineare Algebra" von Albrecht Beutelspacher.

[Anonymous No.6931834]

>>6931166
because it still works. It can be thought of as "holes" instead of electrons (direct current). Google it

[Anonymous No.6931840]

>>6931235
and to transmit via electricity, we use changes in voltage where for a example a high voltage corresponds to a 1 and a low voltage is 0, in binary.

[Anonymous No.6931855]

>>6931304
I dont quite understand you're confusion, but i'll try. put simply, if Det(A) = 0, then A is not invertible, Hence there is no vector x, such that A maps x to b for any x, b.
i.e A*x = b has no solution because inv(A) does not exist.

[Anonymous No.6931858]

>>6931823
Okay. Danke. Das hilft wirklich. Werde mich jetzt halt an die Aufgaben machen und sehen, ob ich die über die Nacht noch bis morgen schaffe alle.

Haben leider kein Buch oder so, lediglich ein 30 Seiten Skript mit den Formeln undso.

[Anonymous No.6932013]

Is the year actually 1714.

[Anonymous No.6932046]

>>6931137
>ratios don't seem rational
I laughed way more than I should.

Anyway n:m!=n/(m+n)

n:m=n/m

[Anonymous No.6932063]

>>6931599
what happens to the three in 2*3=6?

[Anonymous No.6932114]

Babby thermo question:

Why can't a cyclical process be reversible, in theory?

My textbook offers an adiabatic free expansion as proof, under the definition that reversible means it follows the same path to and from its initial state, and that at every point along that path the state variables are in equilibrium . Their argument is that an outside influence would need to do work to return the system to its original state, which would automatically invalidate the reversal.

Any comments or links to reasonable (read: undergraduate) would be appreciated.

[Anonymous No.6932121]

how do i shot web?

[Anonymous No.6932124]

How can the net amount of entropy of the universe be massively decreased?

[poop science maker No.6932134]

>>6931228
it all starts when a cold night a man called maxwell picks up all the laws related to electromagnetism and make the well known maxwell equations(he didn't create all of them nor the theory behind them). Working a little on those equations you can find the diferential operator of waves, which solving it describes waves that moves in a media with a certain velocity:
http://en.wikipedia.org/wiki/Wave_equation

[Anonymous No.6932175]

Tips for reformulating recursive sequences into nonrecursive sequences?

[Anonymous No.6932186]

>>6931589
You would be able to feel it, but it'd probably be faint (depends on the gravity, your initial speed, etc.). You can always detect changes in direction of motion.

Idk what >>6931609 is saying.

[Anonymous No.6932252]

>>6932063
is this a trick question?

[Anonymous No.6932269]

>>6932175
read Generatingfunctionology by Wilf. It has a long discussion of exactly this and it's very easy reading (also it's free via a simple google search).

[Anonymous No.6932291]

>>6931589
No.

[Anonymous No.6932341]

Really hate to ask for help but can anyone please help me out here? What's the answer

[Anonymous No.6932456]

I was telling a friend of mine how I want to learn maths in my spare time and work my way up to the advanced stuff (I'm not that good at the moment). He told me that after 25 (I'm 24 almost 25 right now) that it was near impossible to teach yourself maths because of the elasticity of the brain isn't as great as it was when you were younger.

I was taken back by this, is it true? I mean I know it's not impossible but is it significantly harder the older you get?

[Anonymous No.6932462]

How are photons considered massless when theyre effected by gravitational lensing/.

[Anonymous No.6932464]

Is the volume of an object relevant to his gravitational "force"? i always hear about mass but never volume

[Anonymous No.6932466]

>>6932464
Like the normal force the object exerts? Relative to volume?

[Anonymous No.6932494]

Why would a man being eaten by an anaconda be for scientific purposes? What could possibly be learned from it?

[Anonymous No.6932519]

>>6931214
how can gas solidify? it's gas you dumbo

[Anonymous No.6932538]

>>6932519
>What is deposition?

[Anonymous No.6932544]

>>6931649
Bueno si es que estuviera en mi idioma, o al menos en ingles.

[Anonymous No.6932548]

>>6932341
Grab your textbook and read. The answer is literalty two definitions away.

[Anonymous No.6932684]

What are some good ways to handle studying and such with ADHD without drugs?

[Anonymous No.6932899]

According to Wikipedia, Orion's next test flight will send it on a circumlunar trajectory and is scheduled for 2018. What are they waiting for? Is that how long it takes to analyze the data from the first test? Are they anticipating having to redesign some things after the first test? Something else?

[Anonymous No.6932923]

>>6932684
Regular exercise and good sleep habits can both help with ADHD. Regular exercise makes it easier to have good sleep habits by making you sleepier at night, as long as you don't exercise at night. Both getting more and better sleep at night and being in shape will make you more energetic during the day, which makes it a lot easier to focus. I have experienced this first hand. Many people who have ADHD also have sleep disorders, and that is definitely the case for me. If this isn't the case for you then this might not help you as much as it did me; it's hard to know.

A psychologist told me taking regular breaks to do a small amount of exercise, like a few push ups, sit ups, chin ups, or something like that, tends to be effective at helping ADHD people stay on task, but I haven't tried it.

[Anonymous No.6932964]

>>6932923
Thank you for this post. I try to exercise as much as possible and it really does wonders. I also have a bad time trying to sleep normally and it really fucked me in highschool. Clearly you do as well or I don't think you would be up at this time (assuming you are in a timezone near me)

[Anonymous No.6933048]

>>6932519
>how can water solidify? It's a liquid, dumbo

[Anonymous No.6933071]

>>6931311
Fluids are weird. A good analogy to consider is a glass of water - when you rotate the glass the water inside remains stationary and doesn't immediately rotate (inertia), but friction from the walls of the container will impart rotational energy to some of the water molecules

[Anonymous No.6933082]

Biot Savart Question:

If you have a charge q moving with a velocity V which has components vx and vy. Can you disregard vx at the point of time shown here.
I hope this makes sense, I doubt it does

[Anonymous No.6933086]

>>6933082
>I hope this makes sense

It does not.

[Anonymous No.6933097]

>>6933082
>>6933086

Lemme reiterate,
The velocity of a point charge is given as (1i+2j)ms^-1
The distance from a point at an arbitrary time is (3i)m
If I wanted to find the field produced at that point due to the velocity of the point charge.

Can I disregard the velocity in the x direction since it has no projection on r since they are on the same plane?

[Anonymous No.6933099]

>>6931203
my sides

>>6931278
science bitch

>>6932013
the year is 13 billion something. all other calendars a shit

[Anonymous No.6933200]

>>6933099
Good answer. Are you sure its right?
I said 1714 because for a period of 300 years (dark ages) there are no records, none, anywhere, parish, scientific, art, tax. (Phantom time hypothesis). Either true, fraud or time dilation.

[Anonymous No.6933257]

>>6931165
so why not start with a bio domes, expand them over time and eventually release it to make the whole planet have at least some oxygen so that it can self sustain?

[Anonymous No.6933340]

Cosmology question
In mass density profiles of galaxies

NFW and SIS are 'clouds' of matter over large areas. Are they both just dark matter or can they be dark and normal matter?

point-masses are black holes and such, but also stars and planets? I mean they are very small in radius size compared to galaxy.

What are uniform spheres in this context, planets? Or great clouds of (dark) matter?

[Anonymous No.6933342]

Can anyone explain to me what k-means clustering is/does?

[Anonymous No.6933481]

>>6933257

My understanding of the problem is that Mars has no magnetosphere, which means any atmosphere that we put on it would be (relatively) quickly blown away into space by solar winds. I'm sure the planet's smaller size - and thus, lower gravity - don't help in this regard.

[Anonymous No.6933504]

I have a question concerning parabolas.

I'm studying for my Calc II final exam this week. One of the questions is "Find the area of the region enclosed by the parabola x = y^2 -y and x = y - y^2"

The formula for this is A = integral from 0 to 1 (upper function) - (lower function)

I've never been fond of graphing or memorising certain graphs aside from the basic ones. Am I suppose to know by looking at the functions which one is the upper and lower, or is there another way I can figure this out? I just guessed back when this was covered earlier in the semester on an exam and fortunately guessed correctly.

[Anonymous No.6933519]

>>6933504
1: x = y^2 -y
2: x = - y^2 + y = (-1)*(y^2 -y )

We know that y^2 is opened upwards, so it must be the lower bound, and -y^2 the upper.

You can also get a better image of the parabola by expanding the term and then using the reverse binomial formula a^2 + 2ab + b^2=(a+b)^2

y^2 - y = y^2 - 2*(1/2*y) +(1/2)^2 - (1/2)^2 =(y-1/2)^2 + 1/4

This means it's your normal parabola y^2 displaces by 1/2 to the right and 1/4 up

[Anonymous No.6933522]

>>6933519
Jees, should be -1/4, and therefore 1/4 down.

[Anonymous No.6933581]

>>6933519

Thanks for the informative post. The second option is definitely easier to recognize.

[Anonymous No.6933596]

Would Eris make a better target for New Horizons or not? I know Pluto has more moons (that we know of), but Eris is bigger!

[Anonymous No.6933678]

>>6933340
A uniform sphere model of a galaxy says that the dark matter halo is spherical with constant density around the whole galaxy.

Planets and stars are still point-masses.

[Anonymous No.6933796]

>>6933481
How high would the walls have to be to contain an atmosphere and not have it blown away. (Thinking walling off canyons 'dam' like here)

[Anonymous No.6933807]

is CS a shit major like everyone on 4chan says?

should I switch to math

[Anonymous No.6933882]

>>6933796
8/10 for creativity

[Anonymous No.6933901]

>>6933807
if you're between CS and math then you're probably getting the right side of CS, the theoretical nice stuff. if your program has that, then you're fine, make sure to get enough general math too

if you're in for software eng or even IT / sys eng, then god, yes it sucks

[Anonymous No.6933904]

Light

Photons?
or
Waves?

[Anonymous No.6933913]

>>6933904
Both

[Anonymous No.6933922]

>>6933904
Photons, obviously.

[Anonymous No.6933938]

Hi guys, I'm not very good at linear algebra. I have this linear transformation like pic related, and the matrix A consisting of the three vectors of T(v1), T(v2) etc, isnt invertable. How do I explain wether or not given just this picture that I cant find the standard matrix to the transformation using only the information given in the pic?

[Anonymous No.6933963]

>>6933904
>>6933913
Are they just photons that act like waves (ie move in wave patterns) ?

[Anonymous No.6933967]

>>6933963
they are..something. whether it behaves like a wave or a particle depends on your problem.

[Anonymous No.6933971]

>>6933963
They are things that sometimes behave like particles and sometimes like waves.
You can't put them into either category, and doing so probably impedes your understanding of the matter.

[Anonymous No.6933981]

>>6933904
Both but never at the same time, same thing with matter such as electrons

[Anonymous No.6934026]

Is there a specific website people use to create a CV/resume? That has a template or something? I have an example from a friend in a .pdf and a hard copy example from my professor but they both have the same formatting.

[Anonymous No.6934031]

>>6934026
Most likely some LaTeX or Word template.

[Anonymous No.6934034]

>>6933967
>>6933971
But this is the part I don't understand. In theory, they can be one or the other depending on the problem. But in reality, the light around me right now has to be one or the other (or both at once). It can't 'depend' on anything, it is _______.

[Anonymous No.6934039]

>>6934031
Do you know where I can find a Word template for this? I've never created an academic CV, if that wasn't obvious.

I'm clueless at where to begin.

[Anonymous No.6934048]

>>6934034
> It can't 'depend'
it can and it does. call it whatever you want, its still something that sometimes behaves some way, other times it behaves in another way. thats just the way it is, your intuition doesnt mean jackshit

[Anonymous No.6934062]

>>6934034
>the light around me right now has to be one or the other (or both at once)
Why can't it be something else?

[Anonymous No.6934077]

>>6934048
Are there rules for situations where it behaves differently? Like the light coming off my monitor, what determines if its a wave or particle (or both)? I know my intuition means jack shit but you cant just tell me "light follows no rules except fuck you".

>>6934062
What else can it be if not a wave, particle, or both? I thought that's what we've discovered?

[Anonymous No.6934091]

>>6934026
In europe it is Europass. Its recognised by all the transnational corporations, its what i use when applying outside UK. Google europass cv.

[Anonymous No.6934097]

>>6934077
it cant be a particle, because it is a boson and you can put as many as you want in a given space
it cant be a wave because of the compton effect
it does however behave like a wave in terms of diffraction and interference and it does behave like a particle when you shoot it at a wall.
we dont know what it is, we just descripe what it does

[Anonymous No.6934108]

>>6934097
Got it, that makes sense. Thank you.

[Anonymous No.6934119]

>>6934048
Oh stop with your bullshit already. Photons behave the same way always. It's not like it's randomly behaving however it feels. When people say
>Light is a wave and particle
they actually mean that the most convenient way to mathematically describe such an object is sometimes as a wave and sometimes a particle. Physically, it's always a particle. Particles are defined to have wave-like characteristics. That's why we still call them particles. Particles are defined to be whatever all the fermions and bosons are, period.

[Anonymous No.6934134]

Light is neither a particle nor a wave. Instead it is a quantum field. As a general rule while light is travelling it appears as a wave, but when the light quantum field is exchanging energy with anything it does so in quanta that appear as particles i.e. photons.

[Anonymous No.6934149]

>>6931085
OK, so space is a vacuum, so there's nothing to pull heat away from your body, so if you were just floating in space would you stay warm as you suffocate?

[Anonymous No.6934154]

>>6934149
Even in a perfect vaccum (which you never quite have) you still radiate away a little heat.

[Anonymous No.6934167]

>>6934154
If I didn't need to breath, how long would it take for me to freeze to death by just radiating away heat?

[Anonymous No.6934175]

>>6934167
I'm not the person you asked but am I correct in saying that to figure out this question you would need:
the temperature of the body in degrees
the temperature of the vacuum in degrees
the rate heat transfers to cold in degrees per second
and the lowest survivable body temperature

Am I right?

[Anonymous No.6934176]

>>6934167
approximately <span class="math">\frac{dQ}{dt}=A\sigmaT^4[\math][/spoiler]

[Anonymous No.6934180]

>>6934176
<span class="math">\frac{dQ}{dt}=A\sigma T^4[/spoiler]

[Anonymous No.6934182]

Please explain this to me like I am mentally retarded.

[Anonymous No.6934183]

Was about to make a new thread for this but then i saw this thank god.

I need some help with trigonometry can someone explain how i am supposed to go on about this since not even wolframalpha seems to make sense to me.

I am supposed to simplify and only answer in two decimals.
sin(x+50)-sin(x-50)

Whoever manages to help me get's an early Christmas present.

[Anonymous No.6934184]

>>6934182
x^m/x^n = x^(m-n) and x = x^1.

[Anonymous No.6934185]

What exactly is the kernel of a transformation? Is it just whatever maps to the identity element?

>>6934182
x^(3/2) / x = x^(3/2) * x^(-1/2) = x^(3/2 - 1/2) = x^(1/2) = Sqrt(x)

[Anonymous No.6934186]

>>6934182
x^(3/2)/x = x^(3/2)*x^(-2/2)=x^(3-2/2)=x(1/2)

[Anonymous No.6934187]

>>6931085
wasn't there a philosophy board on this website, 4chan.org?

[Anonymous No.6934193]

>>6934175
I guess the body would 98.6F or 37C?
I thought vacuums didn't have temperature because there's nothing in them, the body would just loose heat through radiation

[Anonymous No.6934196]

>>6934185
Yes.

[Anonymous No.6934198]

>>6934185
>>6934186
thx

[Anonymous No.6934199]

>>6934026
Do it in Latex. Looks way nicer than anything you can come up with in Word.

[Anonymous No.6934201]

>>6934180

That assumes emissivity of unity.

[Anonymous No.6934203]

>>6934193
Even for a perfect vaccum, you can still define a temperature. If you're not in perfect darkness, you're going to absorb radiation as well as emit it. When you absorb radiation you heat up and radiate more. When you radiate, you cool down and radiate less. At some temperate, there is an temperature equilibrium depending on the background radiation.

[Anonymous No.6934204]

>>6934183
sin (x+50)-sin(x-50)=2*cos((x+50+x-50)/2)*sin((x+50-x+50)/2)=2cos(2x)*sin(100)
you could taylor now or something, but i dont quite get your task

[Anonymous No.6934207]

Can someone post the collapse the wave function ice cream comic?

[Anonymous No.6934212]

>>6934193
the universe has some sort of background radiation which can be mapped to a temperature of a black body

[Anonymous No.6934214]

>>6931085
A Carnot engine moves 100 kilojoules of heat and rejects 37 kilojoules. What is the temp of the cold reservoir if the heat reservoir is 370 Celsius?
I can't remember how exactly the original question was worded.

I forgot how to do this type of question so I figure it might have to do with efficiency and put in 230 Celsius as an answer.

[Anonymous No.6934220]

>>6934204
Alright...
If you don't mind can you elaborate a bit on your process? For instance how do you get
>sin (x+50)-sin(x-50)
to this
>2*cos((x+50+x-50)/2)*sin((x+50-x+50)/2)
If you don't want to bother typing. A link to the rules of this would just as good.

[Anonymous No.6934223]

>>6934183
<div class="math">\sin(x+50) - \sin(x-50) =\frac{e^{i(x+50)} - e^{-i(x+50)}}{2i} - \frac{e^{i(x-50)} - e^{-i(x-50)}}{2i}</div>
<div class="math">=e^{50i} \frac{e^{ix} + e^{-ix}}{2i} - e^{-50 i} \frac{e^{ix} + e^{-ix}}{2i}</div>
<div class="math">=\left(e^{50i} - e^{-50i}\right) (-i) \cos(x)</div>
<div class="math">=2 \sin(50) \cos(x)</div>

[Anonymous No.6934225]

>>6934220
http://en.wikipedia.org/wiki/List_of_trigonometric_identities#Product-to-sum_and_sum-to-product_identities

[Anonymous No.6934226]

>>6934183
As said by >>6934223 the expression reduces to:
<span class="math"> 2 sin(50) cos(x) [/spoiler]

If you want to do it manually, the addition rules would be a good place to start.
sin(A+B)=sin A cos B + cos A sin B

[Anonymous No.6934233]

>>6934223
oh yeah, i forgot those *1/2

[Anonymous No.6934237]

>>6934182
<span class="math">$$x^((3/2)-(2/2))/(x^(1-1))$$[/spoiler]
test

[Anonymous No.6934238]

>>6934233
Hang on a second, I think this was given in degrees. You might have to convert the 50 degrees into radians. Euler's formula is in radians.

[Anonymous No.6934241]

>>6933938
v1, v2, v3 do not form a basis of R^3 as v1 + 2*v2 = v3. So the third equality does not give us any extra information (except that t=-4). Therefore your transformation T will not be unique as it is only specified on a 2D subspace of R^3 (the one generated by v1 and v2). It is however still possible to calculate the general form of T. Find it.

>>6934185

Whatever maps to zero.
Identity element is kind of ambiguous in e.g. vector spaces.

[Anonymous No.6934247]

>>6934238
Converting the 50 to radians, I obtained <span class="math"> 2 cos((2 \[Pi])/9) cos(x) [/spoiler] which in degrees would convert back to <span class="math"> 2 cos((40) cos(x) [/spoiler]

[Anonymous No.6934249]

>>6934241
I meant rings instead of vector spaces, woops.

[Anonymous No.6934251]

>>6934237
<span class="math">x^(3/2-2/2)/x^(1-1)<span class="math">
test 2[/spoiler][/spoiler]

[Anonymous No.6934263]

>>6934251
<span class="math">\frac{x^{\frac{3}{2}-\frac{2}{2}}}{x^{1-1}}[/spoiler]
Ayy lmao

[Anonymous No.6934264]

>>6934183
2 decimals is not going to work as it is obviously still going to be a function of x.

I think the point is just that sin(x+a) - sin(x-a) = 2sin(a)cos(x) thus giving you:
constant * cos(x).
It's not getting simpler than that.

Else you left out a crucial part of the question.

[Anonymous No.6934275]

>>6934226
I attempted to do it by the addition rules, here's what i got
sinx*cos(50)+cosx*sin(50)-sinx*cos-(50)-cosx*sin-(50)
But after putting this in wolframalpha i got the answer i was looking for which is 2sin(50)cos(x)

But how do i slam them together so that the final product becomes 2sin(50)cos(x)?

[Anonymous No.6934279]

>>6934275
Sorry, I think I gave you the wrong identity. I have a better one here:
<span class="math">sin A − sinB = 2 cos((A + B) / 2) * Sin((A - B)/2)[/spoiler]

This should give a much nicer output that will resemble the answer you want.

[Anonymous No.6934288]

Lets assume someone solved the collatz problem, proved the twin prime conjecture along with that and used the methods gained from that to fast factor RSA, what should this person do with that knowledge in your opinion?

[Anonymous No.6934295]

I have the unit circle and two points <span class="math">(x_1,x_2)[/spoiler], <span class="math">(y_1,y_2)[/spoiler] on it. Now I want to convert them in polar coordinates
<span class="math">x_1 = \cos(\varphi_1)[/spoiler]
<span class="math">x_2 = \sin(\varphi_1)[/spoiler]
<span class="math">y_1 = \cos(\varphi_2)[/spoiler]
<span class="math">x_2 = \sin(\varphi_2)[/spoiler]


What is <span class="math">|x-y|[/spoiler] written in those polar coordinates?

[Anonymous No.6934315]

>>6934204
Ahh you used this >>6934279 identity now i'm a step ahead.
>>6934279
sinA−sinB=2cos((A+B)2)Sin((A−B)2)
2*cos((x+50+x-50)/2)*sin((x+50-x+50)/2)
Alright cool! This makes sense!

2*cos((x+50+x-50)/2)*sin((x+50-x+50)/2)
2*cos((2x)/2)*sin((2x+100)/2)
2*cos(2x/2)*sin(2x+100/2)
2*cosx*sin2x+50

What did I do wrong?

>mfw i don't get 2sin(50)cos(x)

[Anonymous No.6934325]

>>6934315
This line was incorrect:
>2*cos((2x)/2)*sin((2x+100)/2)

Your first line was correct when it said 2*cos((x+50+x-50)/2)*sin((x+50-x+50)/2)

Your problem was that you took x - x to mean 2x inside the sin.

[Anonymous No.6934343]

>>6934325
Ohh okey so
that makes it 2cosx*sin+50
Why are cos and sin switched?

[Anonymous No.6934350]

>>6934343
They are not. 2cos(x)sin(50) = 2sin(50)cos(x).

[Anonymous No.6934371]

ALRIGHT LET'S RIDE TIME FOR YOUR REWARD

>zenithpasses.com

Sorry guys if i hyped you up. Thanks to all of you though i really appreciate it.

[Anonymous No.6934373]

>>6934371
Maths is its own reward.
and 300k starting

[Anonymous No.6934374]

>>6934373
You're joking right?

[Anonymous No.6934384]

>>6934373
>>6934374
Fuck you i JUST got it.
>it's late

[Anonymous No.6934403]

>>6934207
Anyone?

[Anonymous No.6934426]

>>6934403
I tried.

[Anonymous No.6934452]

Is global warming real?
If it is real, is it honestly as bad as environmentalists say it is or are they just saying that to make some money?

[Anonymous No.6934456]

>>6933504
just a tip for these, I always find the point of intersection and do a rough graph as a sanity check. More often than not it is immediately obvious what goes where after this short step.

[Anonymous No.6934476]

>>6934452

Global warming is real.

The problem is that nobody can agree on the specifics of it. Is the temperature rising or falling? How much is the temperature rising or falling by? Is the temperature rising or falling at all due to human activity? How much of the temperature rising or falling is due to human activity?

It just goes on and on, and there's no single answer to it. Instead we just get a bunch of sensationalist part-truths about muh polar bears and muh carbon emissions and nobody ever comes up with a good idea on how to fix the problem besides throwing money at it.

Also, pardon the /pol/, but there are a quite frankly unsettlingly many accounts of random high-ranking politicians from around the world that say global warming is nothing but yet another agenda to rally and control people a la communism and NWO, but that's where you start to lose listeners.

[Anonymous No.6934480]

>>6931085
>New stupid questions thread because old one is at page 8.
Could you still post in it when it was on page 8?

if you could, don't make another fucking thread, you absolute moron.

[Anonymous No.6934488]

By the way,
>>6934476
>nobody ever comes up with a good idea on how to fix the problem besides throwing money at it.

I realize that this is technically how almost ALL problems get solved, but the qualm I have about it is that it's always at the expense of the commoner, in this case in the form of retarded ideas like the carbon tax. Everyone that is even slightly knowledgeable about global warming can tell you that the biggest aspect of the problem is fossil fuel emissions, the overwhelming majority of which come from cars and power plants.

But the everyman has to be taxed to fix this. It's not like Toyota or Ford has had a quarter of a century to make a car that runs on something other than gas.

Oh wait.

[Anonymous No.6934492]

>>6931333

What exactly determines the amplitude and frequency of an electro-magnetic wave? What is the difference between two colors of different frequencies?

[Anonymous No.6934503]

>>6931304
When the solution to (A-Ex)v=0 is nontrivial (v!=0), the columns of (A-Ex) must be linearly dependent i.e. the matrix is not invertible, thus det(A-Ex)=0

[Anonymous No.6934510]

>>6931589
Gravitational fields are not felt as a force because they apply (approximately)uniformly across your whole body so there is nothing to "feel". You aren't feeling gravity right now, you're feeling the push of the ground on your feet etc.
The situation is different when the gravitational force is different on different parts of your body. Look up tidal force.

[Anonymous No.6934522]

>>6931599
If you're taking the anti-derivative of an indefinite integral then you're getting a double integral...
anti-derivative ~= indefinite integral

[Anonymous No.6934527]

>>6934492
Frequency:
Frequency v can be calculated from the amount of energy E used to produce the photons.
E=hv
Where h is Planck's constant.

Amplitude:
A single photon only has spin and frequency, so I'm pretty sure that this question isn't really valid? Not sure, though. Interesting.

>What is the difference between two colors of different frequencies?
The difference between two colors is caused by by a difference in wavelength (or equivalently) frequency. So the difference is really just the amount of energy "in" the photon.

[Anonymous No.6934531]

>>6934510
this is half true, no offense but have you considered the fact that feeling gravity would be useless to the mind given that it is a constant?

we can feel if gravity were to increase by two, our nerves would pinch and our skin would feel like it was being sucked downwards. the reason we don't feel our current gravity is because we have evolved to be used to it on a physiological level; our nerves have become purposefully unsensitive to gravity because the information is not useful to the brain.

in extreme cases, if gravity increased by 10, you'd feel your skin tearing off of your body in a few hours of duration, your joints would be under severe pain, you'd probably have a powerful headache, and a million other theoretical biological reprecussions; uniformity is only half the reason we don't feel gravity.

[Anonymous No.6934537]

>>6932462
Essentially they have energy and momentum, but no "rest mass"
http://en.wikipedia.org/wiki/Mass_in_special_relativity

[Anonymous No.6934548]

>>6934531
If you're in free fall it doesn't matter how great the gravitational field is. Literally the only thing we feel is a non-uniformity in force across our body, because it stretches/condenses us. If we're in free fall none of that happens and there is nothing to feel.

[Anonymous No.6934560]

>>6934203
not true. Temperature is the vibration of particles at the atomic level, by definition a vacuum contains no particles and therefore has no temperature. Radiation is capable of passing through a vaccuum and affecting the temperature of something on the other side, but a vacuum in itself cannot have a temperature.

[Anonymous No.6934620]

I've been taking anti-depressants on an increasingly random basis
Will this have any negative effects?

[Anonymous No.6934817]

what maths are required in order to start focusing on physics?

[Anonymous No.6934976]

>>6934817

I'm not even really in a university yet, but I've found that everything in physics starts to piece together more easily once you learn basic calculus, and then even more so when you learn vector calculus and you can see the formulas being derived.

[Anonymous No.6934980]

>>6932519
you must be over 18 to post on this website.
did you not fucking learn about the states of matter in 9th grade chemistry or something?

[Anonymous No.6934987]

>>6934620
Yes. Your serotonin levels won't stabilize and you'll feel like shit

[Anonymous No.6934988]

>>6934620
>I've been taking anti-depressants on an increasingly random basis
>Will this have any negative effects?

depends on what you are taking them for. You will get some withdrawal symptoms, make sure you don't cut cold turkey but reduce dosage as prescribed by your doctor.

[Anonymous No.6935022]

>>6934980
>states of matter
>in 9th grade chemistry or something?

What the absolute fuck. I learned states of matter in like 4th or 5th grade and I went to an American Jesus school.

[Anonymous No.6935044]

>>6931158
>there is nobody on /sci/ who knows how photosynthesis work
........

[Anonymous No.6935056]

>>6935044
Magical chemicals known only as "enzymes" and "pigments" soak up car exhaust, oxygen, and light and cast a spell on it to turn it into sugar. Then these magical molecules eat the sugar to fart off tree exhaust.

[Anonymous No.6935088]

>>6931152
Not trees, but I think there are lichens or similar things that could survive there

[Anonymous No.6935113]

>>6934560
the universe has a temperature of ~3 Kelvin due to background radiation

[Anonymous No.6935144]

I've already solved it but I'm paranoid about the answer being wrong (which it most likely is)
Can someone please solve this?
You just have to find the derivative.

[Anonymous No.6935158]

>>6935144
Use the product and chain rule.

<div class="math">\frac{d}{dx} x \int_2^{x^2} \sin(t^3) dt</div>
<div class="math">=\left(\frac{d}{dx} x \right) \int_2^{x^2} \sin(t^3) dt + x \left(\frac{d}{dx} \int_2^{x^2} \sin(t^3) dt \right)</div>
<div class="math">=\int_2^{x^2} \sin(t^3) dt +2 x^2 \sin(x^6)</div>


Too lazy to evalute the integral

[Anonymous No.6935164]

>>6935144
<span class="math">\frac{d}{dx}x\int_{2}^{x^2} \sin t^3 dt = \frac{d}{dx}x(F(x^2)-F(2))=(F(x^2)-F(2))+2x*\frac{d}{dx}F(x^2)[/spoiler]
i think

[Necromancer No.6935294]

>>6931085

Question for bio-fags which isn't really science related.

I want to get a really nice dissecting kit for my girlfriend for Christmas. I thought they were going to be stupidly expensive but then looking them up online they cost like £10-20 each for some of the nicer ones.

I have a limit of £50 to spend.

Any recommendations? I'm in the UK and would prefer not to buy anything from over-seas. I'd love something in a stainless steel case which I could perhaps get laser engraved.

[Necromancer No.6935316]

>>6935294

http://www.brunelmicroscopessecure.co.uk/acatalog/Dissecting_Equipment___Apparatus.html

This one looks good but not 100% sure (The full surgical kit on this page).

Seams like a bit of a measly amount of money to spend; any suggestions for what else to get? She doesn't do a great deal of lab work but I still think she'd like this.

[Anonymous No.6935477]

>>6934560
>Temperature is the vibration of particles at the atomic level
No, temperature is defined in terms of heat exchange and thermal equilibrium.

[Anonymous No.6935489]

>>6935316
>Hobbyist Microscopes
What's the difference between a Fish Disease microscope and a Dog Fertility microscope?

Biology is weird.

[Anonymous No.6935713]

>>6932899
>Something else?
Money.

[Anonymous No.6935782]

any decent introduction books to aerodynamics?

[Anonymous No.6935838]

>>6931285
forgetting vacuum energy here, mate?

[Anonymous No.6935849]

>>6931311
the air is also attracted by the earth's gravity, meaning it behaves much like any other object on earth and thus also rotating with it.

I suppose what gives you troubles in understanding this is that you didn't consider that a large number of weak interactions (molecules of the air being attracted by gravity) can manifest on a large scale.

[Anonymous No.6935855]

>>6931312
Essential Cell Biology really sums up the most important stuff about cell biology in a quite detailed manner.
Start with that and save yourself the zoology stuff for later on, since if you don't really dig molecular biology (read: cell biology), then biology will most likely to be an ungrateful discipline for you.

[Anonymous No.6935869]

>>6931324
About the chloroplasts: cells have mechanisms to detect stuff which doesn't belong there, so the cell will either kill the chloroplast or itself to prevent harm to the rest of the organism.
Some parasites are quite successful in flying under the radar though.

About the bacteria on mars thing:
neither water nor oxygen there, so most likely not. The oxygen part isn't all that important, we got plenty of organisms on earth who live under anoxic conditions, but we have yet to discover life which isn't dependant on water.
Would probably be easier to build a self-replicating machine than to engineer bacteria to live on mars

[Anonymous No.6935880]

>>6934185
I don't see how you get from (3/2 - 1/2) to (1/2).

And without that, I don't see how you get to the solution of sqrt(x).

Am I missing something here?

[Anonymous No.6935881]

let's say i have something like in the picture:
a difraction grating and a single pole a meter or so in distance. will the light bend around the pole, so i can see this effect on a wall in 2 meters from it?

[Anonymous No.6935885]

>>6935880
He got it wrong 1/x = x^(-1), so it's 3/2 - 1

[Anonymous No.6935968]

does anyone have any fiction book recommendations that are must reads? Currently listening to the iliad on audiobook

[Anonymous No.6936040]

>>6935782
Sorry I don't know any in English but if you don't mind Spanish I can name a few really good ones (airspace engineering student)

[Anonymous No.6936047]

>>6936040
I'm actually decent in Spanish but not technical terms. Looking for stability and supersonic=>transonic flight, gracias.

[Anonymous No.6936061]

>>6936047
I hope I can help. How good are you at fluid mechanics? Have you studied it? Are you looking for a qualitative approach ( like, general description of what's going on) or you want some serious text based on the actual equations and science behind it (hence my question about fluid mechanics)?

[Anonymous No.6936067]

>>6935782
Schlichting, aerodynamics of the airplane

[Anonymous No.6936075]

>>6936061
I've done fluid mechanics, I'd like to use actual air given a constant Reynolds number, etc. I've done some computational physics on air resistance before but never on aerodynamics/ballistics.

>>6936067
Thanks

[Anonymous No.6936076]

>>6936047
>>6936061
Maybe you could start with "introducción a la ingeniería aeronáutica" of Sebastián Franchini (one of my teachers, not a specially good teacher but he knows a fucking ton about what he writes in his book. Not related but I have quite a lot of anecdotes about this teacher, I may make a thread some day)

[Anonymous No.6936084]

>>6936076
Thanks

[Anonymous No.6936092]

>>6936075
Ok, then try "Mecánica de Fluidos Tomo I" and "Mecánica de Fluidos Tomo II" of A. Liñan Martínez, M. Rodríguez Fernández and F. J. Higuera Antón (. February 2012)

If you know your fluid mechanics, this has all your answers. Expect heavy theory however.

[Anonymous No.6936112]

>>6936076
Politécnicafag here too. Love ya, keep it going.

Right now doing Civil engineering, and will change shortly to a double on mechanical and industrial design.

[Anonymous No.6936119]

>>6936092
Thanks again, do you have any idea how I can get these in burgerland?

[Anonymous No.6936150]

>>6931085
I'm afraid of sucking dick after reading books about microbiology.

[Anonymous No.6936160]

>>6936119
I am sorry, I don't know, I would only hope those are online somewhere...

[Anonymous No.6936165]

>>6936112
Cómo van los finales? Yo creo que este semestre me llevo un par a julio. De momento voy a año por curso, espero que siga así... Bolonia o plan antiguo? Yo bolonio.

Suerte anon!! (que raro escribir en español esto jajaj)

[Anonymous No.6936171]

>>6936160
I'll try that first. Thank you again, I really appreciate it.

[Anonymous No.6936176]

>>6936171
You are welcome, good luck!

[Anonymous No.6936182]

>>6936171
Oh, by the way, I just remembered. Try ingebook (it's a website). You can find some of the books I use in my classes there (some entirely, some partially available). Hope it helps. If not, there are a lot of interesting stuff you should check out. From chemistry to algebra /calculus and a lot more.

[Anonymous No.6936193]

>>6936165
>>6936165
Si que es raro esto de usar el español en los chanes. Soy bolonio ¿año por año? entonces vas bien,anon. Creo que sólo llevaré una a julio (puta resis). Estoy muriéndome por ponerme con ingeniería mecánica. Tengo a muchos amigos en tu facultad y ahora estaba estudiando por mi cuenta termo, a ostia, me encanta termo.

No te vayas de españa pls, yo puede que me vaya, pero devolveré todo lo que me ha dado mi tierra.

[Anonymous No.6936206]

what kind of life/terrain existed on Mars gorillions of years ago? Microorbial life? Bacteria? Meadows?Fields? and how did it get there? panspermia? abiogensis? what?

[Anonymous No.6936211]

>>6936193
Pues mucha suerte con la Termo, estoy en la especialidad de propulsión y nos dan muchísima termo la verdad. También me gusta pero se complica por segundos. Y no planeo irme de España, de hecho me gustaría dar clases en la politécnica también en algún momento, pero ya se verá. Lástima que te tengas que ir.

Best wishes Anon, wherever it is that you are going.

[Anonymous No.6936238]

>>6936211
>Especialidad en propulsión, en Aeronaitícas
Joder, conozco a tres personas de exactamente tu modalidad (flipo con la idea). Tranquilo, no me iré a ningún sitio de momento. Estoy en Ingeniería Civil, insisto, en tu uni. Está por Atocha mi facultad.
Ánimo con lo tuyo, es realmente increible lo fuertes que podemos ser los politécnicos. Best wishes, anon. I'm sure I'll find you on /sci/ again sometime.
Un abrazo y suerte en Enero.
>>6936206
We still don't know matey.

[Anonymous No.6936295]

What are some good books to read for a last year highschool student who's heading into chemical engineering?

[Anonymous No.6936422]

>>6933200
There is also apparently architecture that is dated at 300 years before it's style/design was seen anywhere else.

[Anonymous No.6936445]

>>6932464
I may be going full retard here. Someone correct me if I am wrong. But I think so.
Based on the formula in
>>6931749
F=G*Mm/r^2
If you had an object that was incredibly long, would the force that a planet's gravity exerts on it not increase as the object accelerated closer to the centre of the planet?

[Anonymous No.6936483]

>>6936206
Mars is said to have lost its water during the 'Venus event', about 80k years ago.

[Anonymous No.6936495]

>>6936445
>increase as the object accelerated closer

of course, the tidal force can even rip it apart

[Anonymous No.6936789]

>>6931311
gravity affects mass... oxygen molecules have mass

[Anonymous No.6936796]

If god created 2 cave systems that is the exact carbon copy of each other as in everything to the single celled bacteria is the same with the same numbers would the cave lifeforms evolve the same way with each other because they're literal copies or will evolution make it completely different environments?

Also the caves would have had 2 million years to evolve but nothing would change geologically or environmentally wise

[Anonymous No.6936797]

>>6936483
kk m8

[Anonymous No.6936867]

>>6936796
>2 million years to evolve

[Anonymous No.6936872]

>>6936796
Well let me be the first to say that you type like a fucking retard.

>2 million years is a drop of piss in the ocean of time.

>Probably the same for a while, though through random occurrences, differences would probably become exponential.

[Anonymous No.6936875]

So I got few questions regarding this entropy thing.

Is it totally impossible to stop it? was this bound to happen ever since the universe began existing? like how when we are born the only thing we have for sure is that we will die, is that how it works?


Also, everything and everyone will "die", and then what? Will the universe remain dead forever? I know time will probably stop existing or some shit, and then what? it will remain as an unchanging empty void forever? I mean, it blows my mind to think that EVERYTHING in space will just get fucked.

Also I read some other theories about the end of universe, something to do with black holes ruining everything, and something about everything being so far apart not even atoms get together, so what the hell is going to happen then?

[Anonymous No.6936886]

>>6936875
0/10

[Anonymous No.6936894]

>>6936886
Why is it bait though, it's a legit question I have, please just tell me instead of posting funny meme pictures mocking my ignorance.

[Anonymous No.6936895]

>>6936875
assuming you mean heat death.
> Is it totally impossible to stop it?
no
> was this bound to happen ever since the universe began existing?
kinda yeah
> like how when we are born the only thing we have for sure is that we will die, is that how it works?
kinda

>Also, everything and everyone will "die", and then what?
things will stop interacting
> Will the universe remain dead forever?
possibly
> I know time will probably stop existing or some shit, and then what?
time continues, change does not
> it will remain as an unchanging empty void forever?
if heat death happens

[Anonymous No.6936945]

why do we make springs and wires in circular coils rather than triangular or squares (which would waste less space)

For a given circular tube capable of withstanding a certain force, how does putting triangular/rectangualar prisms inside of it affect its strength, pic related

I dont know why I started thinking about it but I hate when you think about something and you can't stop thinking about it even though its not really an important or useful question

[Anonymous No.6936954]

>>6936895
That is extremely depressing

[Anonymous No.6937052]

>>6936945
I would have to say that the round tube is a stronger shape for the applications that it is used in ie. cheap camping hatchets. Where as the flat edges of a triangle would probably cave when that hatchet is used as a hammer, assuming the edge of the triangular tube is in line with the edge of the hatchet head.

As far as springs go, that was a good question. At first I thought ease of manufacturing, then I thought of the traditional spirals probably ease of progressive force in comparison to other shapes.
But I realise now why the traditional spiral remains best. Wear points. With a triangular or square type spring, one would have points of wear, where as with a traditional spring, that force is largely spread out over the entirety of the spring.

[Anonymous No.6937055]

Is logic an invention of humans or is it something natural that we try to describe?

[Anonymous No.6937068]

>>6936945


>>6937052 again, I misread the tube one kind of. I think the fractal internal shapes would probably serve to balance out forces placed on the tube. In most cases it may not be necessary however.

[Anonymous No.6937072]

I was having this discussion with my friend the other day and we couldn't seem to come up with an answer, maybe /sci/ has an opinion?

Say someone has the very basics of mathematics down: addition, subtraction, multiplication, division, etc.

How long, in your opinion, would it take an individual to go from their current knowledge to work up to having a decent grasp on physics?

Given that the person studies 5-6 hours a day, has an average or slightly average intelligence, and is enthusiastic about their studies.

Obviously there are tons of variables that can interfere with the progression but let's play the "perfect world" scenario for a moment.

[Anonymous No.6937094]

>>6931221
Radio signals are certainly stopped by thick enough walls or by the ground. Try listening to AM radio while driving through a tunnel.

Metal doesn't so much stop radio signals as redirect them. It's easier for the signal to go through the metal than through air.

[Anonymous No.6937095]

>>6937052
Ahhh... Wear points one is spot on. I wonder if they could be used in something like mattresses though.

Yeah the tube one I'm thinking more pressure on the tube. I don't know if it makes sense but I'd like to see how the tube's strength varied at 2 different points, at the corner of the shape within, and at the center of one of the edges. Then see how that strength was affected as you increase the number of sides.

Then what happens if you put another shape in that shape. Assuming all the shapes are made of the same material.

>>6937072
I don't think that can really be answered with a single number. It depends on the amount of physics you cover, and how in depth you go. "decent grasp" is just too vague. They could get a very basic grasp of physics without any calculus using simple algebra across most subjects withing physics. They just wouldn't be able to go as 'in depth' as someone who had calculus knowledge. There's plenty to learn within physics, even if you only know algebra, though.

[Anonymous No.6937106]

>>6937095
I think the internal shape would be better as a softer/more elastic material than the external tube. so as not to change the tube's shape.

[Anonymous No.6937136]

>>6931312
Thanks man!

[Anonymous No.6937140]

>>6937136
Oops I meant
>>6935855
Thanks haha

[Anonymous No.6937162]

>>6936895
Oh well, at least it's not impossible, I guess.

Just one more thing to whoever wants to answer, are multiverses actually a thing? Is there some proof or convincing theory/hypothesis regarding their existence?

[Anonymous No.6937179]

>>6937162
How dare you even question The Kaku

[Anonymous No.6937199]

what disciplines of mathematics are used in cryptography??

[Anonymous No.6937571]

>>6931166
>What the fuck IS conventional current?

The opposite of real current

>If it's wrong, why do textbooks still acknowledge it and electron flow at the same time?

First Mover Advantage. If a school starts teaching the other way around, every time their students get out a data sheet to look at a component they need, they have to start by reversing all the data. Every time a company provides an "actual current" data-sheet, they pay money to a writer who writes something nobody will download.

The only way to get the standard changed to real current is government action/coercion on a global scale, because no single person, school or company has an incentive to switch on their own.

[Anonymous No.6937602]

>>6931198
>Question level retard here.
>What if we put air between two press and we start to compress this air. I imagine we can't "destroy" this air, so there are a point where the press can't compress anymore ?

Assuming the press and walls are made from an arbitrarily strong material, and you can provide an arbitrarily powerful force:

Air is made from Nitrogen, Oxygen and trace amounts of lots of other stuff (Argon and CO2, mainly).

For simplicity, we'll just assume that air is only Nitrogen and Oxygen.

Under extremely high pressures, if considered individually, both will be compacted into solids. Nitrogen becomes the N4 crystal "Nitrogen Diamond" and Oxygen becomes metastable Tetraoxygen (O4). If you have both of them mixed together (as in air), weird shit may happen but under, again, sufficiently high pressures you will probably get an alloy of metallic nitrogen and metallic oxygen.

Increasing the pressure even further, you can fake the material into acting as if it is part of a dying star massing above the Chrandrasekhar limit. Overcoming the electron degeneracy pressure, you might get photodisintegration and exceedingly high energy physics, combining protons and electrons into neutrons. Your gas is no longer air, it is pure neutronium, and will not become air again if you release it.

Increasing the pressure and temperature even further, the neutronium will collapse into a singularity.

[Anonymous No.6937605]

>>6937199
Number theory, computer science

>inb4 computer science is a science
no, it's part of mathematics

[Anonymous No.6937607]

x / ln(x) = c
tfw cannot solve this

[Anonymous No.6937610]

>>6931235
>Also I don't understand how can you transmit information by using electricity or waves. How does the electricity know what information you are giving her? (I know sounds stupid)

It doesn't.

At the very very most basic, let's say you're in a room. There's a lightbulb in there. You're not allowed to leave the room unless the light is on.

I flip the electric switch (outside the room). The light turns on.

I have now conveyed from my mind to yours, through the means of
MyMind->
MyHand->
Switch->
electricity->
Lightbulb->
YourEyes->
YourMind
the information that you are allowed to leave the room.

The electricity doesn't have any information by itself, nor does my hand, the switch, the lightbulb or your eyes.

Rather, I have used that system to transfer one bit of information to you.

A bit, in Information Theory, is the answer to a single yes/no question, in this case "Am I allowed to leave the room?"

Crucially, bits do not exist on their own. If you did not have the rule "Only leave the room if the light is on," flipping the switch would not have given you information about whether you were allowed to leave the room.

[Anonymous No.6937614]

>>6937607
solve numerically using newtons method (or one of the many approximation methods)

[Anonymous No.6937618]

>>6937607
x/ln(x) = c
x = c ln(x)
e^x = x^c
Now x!=0, so
x^-c e^x = 1
x e^(-x/c) = 1^(-1/c)
Look for real solutions, so consider 1^(-1/c) to be 1
x e^(-x/c) = 1
-x/c e^(-x/c) = -1/c
Lambert's W function is defined as the inverse of f(u) = u e^u
-x/c = W_n (-1/c)
x = -c W_n (-1/c)
Where W_n is the nth branch of the Lambert W function.

[Anonymous No.6937634]

>>6931717
>Why do objects with more mass weigh more? I mean, if you drop a bowling ball and feather in a vacuum they'd both hit the ground at the same time. So Earth must be pulling both objects towards it with the same amount of force. But then if I'm holding the bowling ball in one hand and the feather in the other, the bowling ball feels like it's being pulled with much more force.


This example is easier with same-material weights, so that's what I will use.

If you drop 1 lb lead weight and a 10 lb lead weight in vacuum, they'd both hit the ground at the same time. But if you're holding one in the one hand and the other in the other, the 10 lb weight feels like it's being pulled with more force.

Yes. It's being pulled with 10 times as much force.

Take your 10-lb weight. Replace with 10 x 1-lb weights. Total weighs the same as before.

It should be clear to you that even though gravity pulls ten times as much on the arm holding ten weights, they should not fall faster just because there are more of them. Each weight falls at the same speed, no matter whether it's the single weight in your right hand or the ten weights in your left. If you take the ten weights and combine them (Melt them together, put them in a bag, whatever), they still don't go faster.

Discard the weights, replace with individual mass units. Your feather is composed of, say, 3 gram. Your bowling ball of 20000 gram. But gravity works, much like on the weights, on each mass unit individually. Each gram experiences the same force, and therefore falls at the same acceleration. Just because some of the grams are showed close together (in a bowling ball now, instead of in a bag), they don't fall faster.

[Anonymous No.6937640]

>>6932456
>I was telling a friend of mine how I want to learn maths in my spare time and work my way up to the advanced stuff (I'm not that good at the moment). He told me that after 25 (I'm 24 almost 25 right now) that it was near impossible to teach yourself maths because of the elasticity of the brain isn't as great as it was when you were younger.
>I was taken back by this, is it true? I mean I know it's not impossible but is it significantly harder the older you get?

My personal experience is that he's probably not wrong for an average human but are you average? I mean, truly average? Does the McHamburger guy handing over your order seem like he has a 50/50 chance of being smarter than you?

If you are the kind of guy who hangs out on /sci/, you are probably in college or equivalent.

You are definitely the kind of guy who has the kind of environment where you think "I should teach myself math in my spare time" won't get you labelled as a freak.

That's not an average environment. It feels natural to compare yourself to your friends, family and acquaintances and say "I'm about as smart as other people are," but that's not an average group. You share genes and values with your family, and have, consciously or not, selected your friends from other people who have approximately your values, who have gone to the same schools or had the same jobs as you.

The truth is, if you feel average, you are average compared to a group of people who are all, much like you, filtered for intelligence or conscientiousness.

Go learn some fucking math.

[Anonymous No.6937642]

>>6932494
>Why would a man being eaten by an anaconda be for scientific purposes? What could possibly be learned from it?

Mainly you'd be learning exactly how diamonds it makes all the vore fetishists out there.

[Anonymous No.6937650]

If humans ever achieve the capability to travel faster than the speed of light, does that mean during the time travelled, we won't perceive anything because it (light and sound) hasn't reached us yet?

[Anonymous No.6937656]

>>6937618
-x/c e^(-x/c) = -1/c
-x/c = W_n (-1/c)

could you explain that step?
why isnt W(-x/c e^(-x/c))=1?
sorry if im being stupid here

[Anonymous No.6937659]

>>6937656
Definition of inverse function.
If W is the inverse of u e^u and
u e^u = 1,
then
u = W(1).

[Anonymous No.6937662]

What is the point of teachers/professors giving noncalculator tests/quizzes? If someone pursues a career that involves mathematics, is it not obvious/implied that the person will always have a calculator handy while working? Obviously it's good to teach how to do something without a calculator, but after that, why bother?

[Anonymous No.6937663]

>>6937659
oh yeah i was retarded. thx

[Anonymous No.6937684]

>>6937662
Past school I never had any non-calc test/exam that involved any calculation. Pretty much every single exam I did (math/commerce) you were allowed calculators because they are testing on application and analysis.

[Anonymous No.6937693]

>>6937684
Interesting. I wish that's how our math teacher would do it. But instead he chooses to poorly teach and prepare us for tests/quizzes and then gives tests/quizzes at a college level, quizzes being typically noncalculator and tests having a calculator section and a noncalc section. Only one kid in the class has an A and there is a 10% grade gap between him and the kid(s) with the 2nd highest grade(s). It's as if he is targeting the 1% of the class that can survive with little to no explanation. It is absolute bullshit and he simply should not be allowed to teach math. Funny thing is that he's an amazing and topically immersive physics teacher. I have an 85% in his AP Physics B class (his tests are previous AP tests and quizzes are individual AP problems, on both tests and quizzes, he includes AP Physics B and C problems) and 72% in his AP Calc BC class. I want to confront him, but I feel like being blunt with him and his method of teaching Calc will screw me out of a letter of rec because I was a blunt prick.

[Anonymous No.6937700]

>>6937693
>college level
sorry that might be confusing considering it's an AP class. What I meant was that they're harder than AP should ever be.

[Anonymous No.6937714]

>>6937662
Any serious math done at a college level probably should not involve a calculator. It should be sufficiently abstract, conceptual, or proof-based to make a calculator only good for smuggling notes into a test.

[Anonymous No.6937718]

What would happen if the earth's rotation speed accelerates a little bit?

[Anonymous No.6937719]

>>6937718
You would fly out in space along with the atmosphere and all the oceans. You don't want earth's rotation speed to accelerate a little bit

[Anonymous No.6937737]

What's the hardest ceramic currently known?

[Anonymous No.6937808]

If
>0.5% of all people are engineers
>7% of all people are gay
>7% of all gays are engineers

what is the probability that a given engineer is gay?

[Anonymous No.6937821]

>>6937808
Lel

[Anonymous No.6937825]

>>6937808
Gay engineers amount to 7/100 multiplied by 7/100, or 49/10000 of the whole population, while engineers amount to 5/1000 of the whole population, 49/50, or 98% chance that a given engineer is gay, under the conditions given.

[Anonymous No.6937849]

got exam on introductory electromagnetism (coloumb's law, potential difference, maxwell's equations, poynting, phasors etc)

what do

[Anonymous No.6937868]

>>6933200
>I said 1714 because for a period of 300 years (dark ages) there are no records, none, anywhere, parish, scientific, art, tax. (Phantom time hypothesis). Either true, fraud or time dilation.

Ah yes, that hypothesis.

It's racist as fuck. By that, I don't mean in the SJW style of "weh weh the truth is hurting the feelings of niggers," I mean "The guy who made it up only cares about white people so he didn't check if the Chinese have any records."

Let's say you have a record at 1100 and another at 1400. You have none in between.

In the 1100 document, it says "The Chinese call this "The Year of Our Dog

In the 1400 document, it says "The Chinese call this "The Year of Our Seven Leaping Assholes."

You find no documents in between, so you conclude that there's a fake 300-year gap.

Meanwhile in China, you find Chinese records that go Dog/Ape etc. for 300 years until it ends with Year of the Seven Leaping Assholes but clearly that's not evidence because it wasn't written by a white man.

[Anonymous No.6937878]

>>6934476
>Also, pardon the /pol/, but there are a quite frankly unsettlingly many accounts of random high-ranking politicians from around the world that say global warming is nothing but yet another agenda to rally and control people a la communism and NWO, but that's where you start to lose listeners.

This is true.

This is also something that does not convey any evidence about the truth/falsity of global warming, because this happens for all issues - if false, by honest politicians trying to protect their constituents. If false, by crooked politicians cynically manipulating their constituents.

[Anonymous No.6937891]

>>6936119
>Thanks again, do you have any idea how I can get these in burgerland?

I haven't checked, but Amazon is just amazing for almost everything, really.

[Anonymous No.6937893]

>>6937868
The chinese records don't talk about the west. So in reality ancient China was 300 years more advanced than we thought it was.

[Anonymous No.6937897]

>>6936445
>If you had an object that was incredibly long, would the force that a planet's gravity exerts on it not increase as the object accelerated closer to the centre of the planet?

That formula only works for point masses. If you want it for weird shapes, do a FEM analysis.

[Anonymous No.6937983]

>>6931589

Remember the most wonderful thought that Einstein ever had "A falling observer cannot feel their own weight" Minus tidal forces you will not be able to tell what your trajectory is because you are standing still it is space around you that is curved and moving relative to your perspective.

[Anonymous No.6938294]

>>6936945
A spring is subject to tension and compression. Any sharp corners are likely to tear or crack. A round spiral profile has no 'corners' for crack propagation.

[Anonymous No.6939186]

Hypothetically speaking...is animal uplifting possible? (uplifting would basically be like genetically engineering a dog to have human intelligence)

Probably not, but was curious.