/sci/ - Science & Math

Unanswered questions:
Physics questions:
>>11028739
>>11028811 (chemists should also know this one)
>>11032982
>>11033247
>>11034125
>>11037938 followed up by >>11037943
>>11039256

Chemistry:
>>11036666

Maths:
>>11034152
>>11036078
>>11039757 (I think so, yes)

Geology:
>>11040400

Share your thoughts:
>>11029712

/adv/
>>11030878
>>11033476
>>11038105

Stupid questions:
>>11033663
>>11033885
>>11035880
>>11039486

I used to just lump in advice requests with stupid questions. Thoughts?

>>11028739
Solid materials are incompressible, so no. Conductivity is a function of temperature.
>>11028811
No. The charges from the ions are enough to balance themselves out.

Question on statistics.
Lets say your chance of success is p=.007 in n=100 trials. You want to win once, x=1 in those 100 trials.
I just do a binomial distribution, B(1;100,.007) but that gives you a rather high number of .8.
As an alternate solution, I did x=0 and got an appropriate answer, where i did 1-B(x;n,p) which sounds correct since it is also equal to 1-.993^(100)
So why doesn’t the first approach work?

How long takes to a person with slightly above average I.Q. to learn all math of high school?

>>11040841
If you’re implying you have slightly above average IQ, you don’t because you don’t know “”””all of highschool math””””

>>11040841
probably a year. 2 years if you include calculus.

>>11036078
Show that m^3 can only be congruent to 0, 1 or 6 (mod 7).
And that 10^(3n+1) can only be congruent to 3 or 4 (mod 7).
Obviously none of 0+0, 0+1, 0+6, 1+1, 1+6 or 6+6 are congruent to 3 or 4 (mod 7).

I don't know how you prove this, because I don't know number theory, but that's how I'd do it.

>>11040846
Shitty tier school in 3rd world. Never get less than a B in math, and still a John Snow.

>>11040805
if you're using R pbinom calculates P[X<=x], not P[X=x]

If gravity is indistinguishable from acceleration, does that mean the earth's crust is actually accelerating outward?

And does that mean that the sun is just accelerating matter through time, so that spontaneous fusion which would take billions of years happens in seconds?

>>11041039
>earth's crust is accelerating outwards
Inwards, actually. That's why the earth rotates.
I can't read the remainder of your post.

I'm trying to get x on one side of this rational expression, i just can't do it. Any tips for how to deal with this?

>>11041088
y=4x+3/3x-2
3xy-2y=4x+3
3xy-4x=3+2y
x(3y-4)=3+2y
You should use associativity accordingly to have the expressions with the variable you want in one side. Factoring is your friend when you want to isolate a variable from multiple expressions after all, so you want to make it as easy as possible. At least with the more common operations, when other stuff like composition comes into play it can get harder, sometimes even impossible.

>>11040740
>Thoughts?
It's good. Being more organized is always a good thing.
>>11029712
Music theory.

Are there any good resources to help me learn how to sketch graphs? I don't understand how I can at a glance sketch out something like y = (2-2lnx)/x^2

>>11041185
x=0 will tell you where it crosses the y-axis, and finding zeroes of the function and its derivative will tell you where the function crosses the x-axis and when it changes from decreasing/increasing, etc.

>>11041192
Okay, I just need a lot of practice I think

Thanks

>>11040680
Why repeatedly applying a a function f(x),f(f(x)),f(f(f(x))) ... eventually lands on a fixed point?

>>11041218
check this out real quick

https://youtu.be/8l-La9HEUIU

>>11041241
Not always, consider the successor function over the natural numbers.

My question is a bit out of the ordinary, but I hope you guys can help me:

>Faced with math question
>Work out the answer within a few seconds, without really thinking
>Brain panics
>Assume I'm completely wrong and then do the working out in my head
>Was right all along, so it was a waste of time

How can I believe in myself more when it comes to math? Hell, when I had a math tutor in high school, he'd constantly bring up that I need to believe in myself more.

Are trig identities commutative? If you write this problem over 1 and then multiply the top and bottom by 2, can you rewrite 2ΘcosΘsinΘ as 2sinΘcosΘ = sin2Θ? It would then just be Θsin2Θ in the numerator?

>>11041617
Of course you can do it, it's just multiplication.

>>11040680
Hey fellas. I'm kind of in a tough spot. I have a set of motor velocities and corresponding powers in a scatter plot. Problem is, it kinda looks like shit.

I want to have one or two lines of best fit for my power to drive model. How would I even begin to know which points to exclude? The black lines are what I estimate as a best/worst case power-to-drive, but I'm genuinely unsure what to make of the cluster of points near the bottom-right (consuming no power when at 80kph seems unlikely)

I don't even know what statistical techniques I can use to say "Between these two lines lie most of my points", and I don't know how to deal with data that is *this* noisy. any and all help is appreciated.

in set theory when a set is just called 'infinite', is it assumed to be uncountable infinite?

>>11042268
No. When it's assumed to be uncountable too, it's mentioned, unless there is a typo/mistake.
>>11041407
Fast vs slow thinking. You're not wrong for going over it carefully and checking if you didn't make any mistakes, I do that too. However, when you have little time, you just have to be rational about it and just go as fast as you can. If you find that impossible, maybe talk to your psychologist.
>>11041241
Repeatedly applying a function almost NEVER lands on a fixed point. What ON EARTH are you talking about?

>>11042268
>in set theory when a set is just called 'infinite', is it assumed to be uncountable infinite?
no. it literally means countable or larger.

>>11042280
>>11042283
thanks

>>11041617
this was the problem I posted a meme instead

>>11040400
Look up albite twinning.
Also Plagioclase has cleavage and is usually darker than Quartz.

A set like this would be just one element?

>>11042768
No, it has at least like, two elements.
Maybe three.

>>11042783
Which would they be? how would I describe them?

>>11042816
Maybe [math]\frac{1}{2*1} - \frac{1}{3*1}[/math] and [math]\frac{1}{2*2}- \frac{1}{3*1}[/math]
There might be some more, tho, since the set goes through all numbers that can be written in the form in your picture for natural n and m.

>>11042816
hope this helps

What would be the minimum number of clusters to achieve the state as shown on the image where the red cluster only consists of of the points that make the left eye? I haven't really been able to get it down from 7 to less clusters. If anyone wants to play around with the visualization, https://www.naftaliharris.com/blog/visualizing-k-means-clustering/ and choose the smiley face preset

>>11042831
like this?
I'd say 4 since a triangle is the smallest polygon, 3 edges would be needed

>>11042842
yes like this. however, would it also stay like this if you run it through a couple of iterations? i tried out the pattern and it always seems to fail and divide the space into four quarters of about the same size.

>>11041088
thank you anon. I've got another one grinding my gears.

>>11042906
meant to reply to
>>11041146
Thanks again for the help

Are the recommende sci Wiki books good for complete mathlets?

>>11042855
hm no...
placing one near the eye and 3 in top left of it close together with the other 2 spread a bit on other side I can get it to go through 5-6 iterations before the red eventually pushes through 2 of the 3 on top left though... I think it's never going to be stable for n<7

Should I read Fruits Basket, or watch the new or old one?

can someone tell me why the answer isn't 5.58 V/M

>>11042997
turns out the stupid cunts are using two different values for the resistivity of nichrome between the book and the homework

god I fucking hate this textbook

>>11042997
That's correct for a resistivity of 1.5e-6 Ωm, which is around the upper end of the range for NiCr at room temperature. The actual figure depends upon alloy and temperature.

>>11041241
Not all functions have fixed points. Not all fixed points are attractive (meaning that iterating on a value near a fixed point results in a value which is nearer to the fixed point). For an attractive fixed point, the basin of convergence (the set of initial values which converge to the fixed point under iteration) is typically not the entire domain of the function.

E.g. consider the Mandelbrot set generated by the family of (complex) functions f(z)=z^2+c. For values of c in the large "cardioid" shape on the right, f^n(0) converges to a fixed point. For values of c in the circular bulb on the left, the iteration alternates between two attractors; in the largest bulbs above and below the cardiod the iteration cycles through three attractors. As the bulbs get smaller, the number of attractors in the cycle increases. Outside the set the iteration diverges.

What is the pattern for numbers that are multiples of 2 but not 3?

what are some physics books for beginners that cover every topic?

im going over some old uni work to try to stay sharp and im stuck already.
why is the underlined statement true?
[math] p_1,...,p_n [/math] are necessarily odd, being of the form [math] 4n+1 [/math] so surely [math] m [/math] must be even?

>>11043264
2 4 8 10 14 16 20 22 26 28 ...

>>11043287
i know that but i want to know how to write it out mathematically

>>11043298
x|2 & !(x|3)

>>11043298
In words: the set of even numbers that are not multiples of 3.
In symbols: [math] \{2n:n\in\mathbb{N}~~~\text{and}~~~3\not\mid n\} [/math].

Is there a limit on retention of things you read? realistically how many books should someone read a month before it just stops getting remembered? I've started reading for a couple hours a day and I'm wondering if you can read "too much"?

>inb4 nooo I want an arithmetic formula

>>11043355
Don't be a puss. None have found a limit.

I'm so confused about where to even begin for this problem. We've only really learned about continuity so far. Any tips?

>>11043360
i do though

>>11043364
so the actually quantity I read won't effect retention of what I read? i.e if I read to much I won't be 'pushing the old stuff out'?

>>11041938
if there's that many points below your "worst case" line then obviously something is very wrong with your model and/or your data, and no fancy statistical technique will bail you out

>>11043281
it's not true, all the primes are 1 mod 4, you multiply them and the product in mod 4 is still 1 mod 4, you add 1 and it's 2 mod 4, definitely even
you can even give it some values, like 5, 13 and 17, which are all 1 mod 4 primes, and you get
(5*13*17)^2+1
1221025+1=1221026, even too, and obviously adding more odd (1 mod 4) primes ("all" of them) will not change the outcome of it being even
then again the text also says
>there are only finitely many primes p with p = 1 mod p
which doesn't make sense cause that'd imply that 0 = 1 mod p

>>11043268
university physics by young and freedman

>>11043369
the only way h could fail to be well-defined is if h(x)=infinity or -infinity. the first case is easy to rule out (why)? to rule out the second, try plugging c into the first equation and see what you get

>>11040680
Does masturbation in the shower affect the ecosystem of the teenage mutant ninja turtles?

>>11043396
The first equation being |f(x)-f(y)|<L|x-y|?
We know that f(c) > -infinity for all c (I think that's what the claim means, I think it's saying there is a lowest bound for all f(c)), but wouldn't plugging in c to that equation just give us 0? Also, is the first case easy to rule out because if h(x) -> infinity for some x, then it means that one of the functions in the set is growing without bound (so it's not L-Lipschitz, I think)?

>>11043411
if I said yes would you stop beating off in the shower?

>>11043437
They call me the shredder

>>11043423
>>11043396

Actually wait, since |f(x)-f(c)| < L|x-c|, we know that the distance from f(c) to f(x) must be within a linear combination of x and c. Since we're never plugging in x = -infinity, we know that f(x) would never be infinitely large. Also f(c) != infinity so it must be some constant. this isn't formal but I think I'm on the right track?

Is there a book about writing formal proofs for someone who never did one?

>>11043423
>The first equation being |f(x)-f(y)|<L|x-y|?
yes
>We know that f(c) > -infinity for all c
No, it's saying that there is some c and some finite number M such that for all f, f(c)>M. If this is not immediately apparent to you, you need to review the definition of inf
>wouldn't plugging in c to that equation just give us 0
No, you get |f(c)-f(x)|<L|x-c|. Given this equation, for a fixed x, think about how to get a lower bound for f(x). That is, you want to write f(x)>(something) where the something is finite and does not depend on f. Once you have this, you can conclude the infimum is not -infinity.

is the l.u.b property usually taught in pre-calc? my prof is a sperg who insists on proving everything and i'd like to know if i can gloss over shit like this for now.
>inb4 underaged
im not, unfortunately.

what's a simpler way to prove that for any epsilon > 0 it's always possible to find a natural m such that
[math] \sum^{\infty}_{i=m+1} \frac{k^{i}}{i!} [/math], where k>0?
it's to prove that a sequence of polynomials is cauchy.
one way i can see is rewriting it as a sequence [math]x_m = e^k - \sum^{m}_{i=0} \frac{k^{i}}{i!} [/math] and using the taylor series expansion to show that by definition the whole thing goes to 0, and then use the definition of convergence f a sequence of real numbers to show that such an n has to exist for any epsilon.
but that seems a bit convoluted, making a new sequence and then using convergence to bring the result to the original inequality feels a bit non-constructive and i'm not too satisfied with that, don't know if my prof would be either

>>11043587
>the entire sum converges
>the remainder of the sum goes to zero from the definition
It's that easy.

>>11043604
By the by, it only works for fixed k, and the result is false if you let k change.

Can science explain why I desire to be feminized and used for the pleasure of real men?

>>11043604
>>11043621
thanks, for some reason it didn't sit right with me but it makes the most sense so i'll go for it
and yeah k is fixed, forgot to add that

>>11043628
seconding this, it's for a friend of course

>>11043471
Sorry, I meant f(c) > -infinity for all f, not for all c.

Then, f(c) > M. And because f is L-Lipschitz, we know that L|x-c|+M <= L|x-c|+f(c) <= f(x). So f(x) is bounded below. Therefore, there is a finite lower bound for {f(x): f in F}. So that means h(x) != -infinity.

And I guess I also have to show that h(x) has a finite upper bound (informally h(x) != infinity). If h(x) = infinity, then all the functions at x evaluate to infinity (how would I say this more formally?), but since x is still a real number, L|x-c| is still a real number and |f(x)-f(c)| would need to be bounded by this (so f(x) can't go to infinity).

>>11043722
>L|x-c|+M <= L|x-c|+f(c) <= f(x)
should be -L|x-c|+f(c)<=f(x) but other than that looks good

>>11043737
whoops yeah.

Also I think that as long as I show that (for all x) there is always a finite lower bound to {f(x) : f in F}, then I've proven that h(x) is well-defined (since h(x) is defined as the lower bound to {f(x): f in F}). So I think I can ignore the second half of my post >>11043722

>>11043628
Science says that you have a female brain and should probably speak to a gender therapist.

I'm a stupid fucking idiot and can't for the love of me understand differential calculus. Does anyone have like a guide or a step by step video for an idiot like me? I'm absolutely lost and it's only the first week.

>>11043849
Hmm... not the guy you're replying to but I too have feminization/crossdressing/submission fetishes and am quite content being a man in my daily life.

In vector projection (a.b/b^2 * b), b^2 accounts for the possibility that b is not a unit vector.
Does this mean b must always be a unit vector along a single axis for this to work?

Is the timing of an event information? If I had two entangled particles attached to a clock prepared with instructions beforehand (i.e collapse at 12pm means go forward, 6pm means turn around) that somehow knew WHEN the other was measured I could transmit information FTL breaking causality and therefore impossible. Then what about simultaneity, what effect does it have on the timing of entangled particles?

>>11043628
That's a perversion of the desire to be purified and used by Jesus to help others.
>>11044108
Calculus Made Easy has worked for over a hundred years.
>>11044184
No, because we're accounting for when it isn't.
Also, I have absolutely no idea what you mean by a vector along a single axis.
Finally, holy shit that notation my fucking eyes, even physicists aren't that bad.

>>11043628
Have you had much success in relationships?
If not, it could be a desire to become what you are having trouble obtaining.

Is the speed of light c because that's the "speed limit" of the universe, or is c the speed limit because it's the speed of light?
Like, if the speed limit was higher, would light travel at that speed or would it still be 300.000 km/s?
Why is c that number and not 870.000 km/s or any other number?
I'm not even sure I'm asking the question properly

>>11044317
The speed of light is an empirically observed quantity, but it's measured in units of metres per second, and the metre is defined so as to fix the value of c at exactly 299792458 m/s.
In other words, a parallel universe identical to ours except with a doubled value of c (but retaining the same convention of c = 299792458 m/s), would have a metre that's half the length of ours. Does this mean that if the speed of light doubled tomorrow, the physical consequence would be that the metre halves? It should be, since our current theories of physics tells us that c is a universal constant, so any change in that value should have 'universally' observable consequences.

Hi /sci/ I'm asking you guys a homework question.
Given the matrix A = [1 3; 1 -1] find all A invariant subspaces of R2
My approach to this question:
1. Show that the zero vector is A-invariant and conclude that the zero subspace is A invariant
2. SHow that a plane in R2 is A-invariant and conclude that the entire R2 is A invariant
3. Show that a line in R2 is NOT A invariant (I need verification for this):
Assume that a line is A invariant, then [math]Av = \lambda v \text{ where $v$ is non-trivial}[/math]. Would it suffice to show that [math]A \ne \lambda[\math]?

>>11044531
{0} and the whole space are trivially invariant, other subspaces follow from the analysis of eigenvalues. what are the eigenvalues ?

>>11044542
I don't think we are supposed to solve it with eigenvalue/vectors since we are not taught that yet.

>>11044545
finding invariant lines is literally finding eigenvectors

>>11044554
>>11044542
bigger brainlet than the person asking the question, desu.
>>11044531
do your own fucking homework

>>11044569
Well this is the sqt and I have a question. I don't see what's wrong with having someone answer my doubts. Where'd you suggest I ask this instead then? In a new thread?

>>11044569
do you disagree with something ?

>>11044531
Your proof strategy up to 3 is good, but that one is goofy and showing that isn't sufficient.
Since A sends R^2 to R^2, lines are the only possible nontrivial invariants.
Suppose v is some element such that Av=λv and compute to show this doesn't happen.
>>11044569
>he tells people to do their own homework in the homework thread

>>11041070
>I can't read the remainder of your post.
Regarding proton stability:
>Despite significant experimental effort, proton decay has never been observed. If it does decay via a positron, the proton's half-life is constrained to be at least 1.67×1034 years.
Assuming it's not just a crackpot theory, would a massive object like the sun be able to accelerate time, so the half-life to an outside observer was <1 second?

Is it true that your gpa is a blank slate after transferring from community to university? Pls say yes

>>11044745
i think it depends on the college and university but all the summer CC credits i transferred didnt affect my gpa

so for some assignment i found dP/dt just over two seconds of the graph, i then later use that dP/dt to multiply by dV/dP to end up with dV/dt. From there i moved the dt to the other side and integrated both sides for V = ... * t.
for this integration am i supposed to keep the integral bounds from 0 to 2, or add a constant of integration C?
so basically would it be
V=...*t + C
or
V = ...*2 - ...*0 = ...*2
pretty simple question i just dont know which to do

If the weak force is mediated by massive bosons does that mean the weak field doesn't change at the speed of light? If so how fast should it theoretically travel?

>>11044674
Gravity being the same as acceleration simply means that you can't tell the difference between the two.

Time actually decelerates in a gravitational field, I'm pretty sure that your idea makes sense but you would probably need a black hole to produce that much gravity.

>>11044818
So from google: The gravity at the sun's surface is [math]274\frac{m}{s^2}[/math]
The gravity of the sun, R=432,000mi, at one earth's radius from the core, R=3,960mi, is [math]3,260,000\frac{m}{s^2}[/math]
At 100mi from the core, the gravity becomes [math]5.1 billion\frac{m}{s^2}[/math]
How would I calculate the time dilation caused by this?

so for my calculus class we're computing limits but we aren't allowed to use L'Hopital's rule. Rather, our teacher gives us a bunch of limits that we take as true and we have to use them as well as the rules for composed functions and multiplication of limits in order to compute the value for the more complicated limit.

Are there any textbooks or online resources where I can find practice problems for limits with this kind of approach?

>>11044847
Also by googling
https://en.wikipedia.org/wiki/Gravitational_time_dilation

Under the outside a non-rotating sphere part.

General relativity is pretty complicated though so you have to make a lot of approximations.

>>11044794
i guess the problem is not good if i do have to bound from 0 to 2 as ultimately i want V in terms of t to plug into a different equation to set that in terms of t

>>11044847
pretty sure the gravitational acceleration 100 mi from the sun's core is around 0 m/s^2.

>>11044866
what textbook are you using?

I don't understand what they are doing in the first step. How do they go to sin(1/x) / (1/x)? Where did the 'x' of xsin(1/x) go? 1/x is the argument, but how does the sin get into the numerator?


In the differential equation, how do I setup the system of equations from here? All the homework sites say you setup an equation =1 for sinx and =0 for cosx, but why?

Is it because the answer needs to equal 1sinx? So since there is no cosx in the answer, the cosx has to be equal to 0? I don't understand why we can be sure that both equations added together won't equal sinx.

>>11045388
x*f(x)=f(x)/(1/x) anon. Do you see how this would be useful for finding the limit?

>>11045388
x = 1/(1/x)

Let x=2
2 = 1/(1/2)

>>11045388
The first two questions in your first paragraph are connected and after a moment’s thought should resolve your problem all at once.

>>11045388
x=1/(1/x)
If you want you can write it as (x^-1)^-1, it's pretty easy to see like that
And yes, what you wrote at the end is true, answer has no cosx so it's coefficient has to be 0
>I don't understand why we can be sure that both equations added together won't equal sinx
It's just evaluating the derivatives of the general form of y, and computing the sum. Derivatives of sinx can only ever give you múltiples of cosx or sinx, from there you just associate to get the equations you want.

>>11044262
>Calculus Made Easy
Thank you!

>>11044574
>immediately pivots to another venue for begging for help instead of doing his own work
have fun on your exams

/eng/ is dead right now so I'll ask here
what coefficient is PM? D and L are drag and lift.

>>11045845
Post the context

>>11045848
It's regarding changes in downforce and drag in the 2019 Corevette ZR1
I forgot abbreviations would be at the end like an idiot, it's the pitch moment coefficient

>>11045851
>>11045848
Also I realized I didn't even post the screenshot, long day
No use in posting it now but whatever

im dont understand logic
can someone help plese

>>11045854

pitching moment
[eqn]C_{PM}=\frac{\text{moment from drag and lift}}{\text{dynamic pressure}\times\text{surface area}\times\text{length}}[/eqn]

>>11045860
c'mon dude
7 doesn't follow from anything (missing a not for P)

Anyhow, you did get ~P.
This will give you R from line 1.
Then you're basically done, since you get the final implication.

>>11045871
I was thinking the P in 7 gets double-negated or something
P and R then not S ?
Or do I need to find the value of R first..
I just started learning this from youtube videos so ye

How do you learn to learn ? Are there people that just get it from the start ? Is it luck ? Are there any methods that will propel anyone to excellence or is it a matter of hours reading books and doing the exercises ?

>>11045890
>I was thinking the P in 7 gets double-negated or something
>P and R then not S ?
no

>Or do I need to find the value of R first..
no values, just get the symbol R soundly as a consequent
it's all symbol manipulation

>>11045902
have iq

don’t be low iq

can someone help me with this? i feel like im forgetting the identity i need to prove this

>>11045941
nvm i see it

>>11045941
>>11045946

What book would you recommend for a review of calculus up to vector calculus, and linear algebra. And directions to go after that, say statistics? Also has self learning helped any of you with your career?
Im a biochem grad but dont want to spend my life waiting, purifying proteins and running gels. I'm hoping to join a comp bio lab. So maybe anything useful for CS and stats?

In 2D physics, assume I have a rectangle of some mass, and the rectangle is NOT fixed at any pivot point. It can move freely in space.

If I push it with my finger, will it always rotate about its own center of mass? or does my finger cause it to rotate about some new rotation point?

>>11045967
>reviewing calc
Spivak.
>multivariable
I like Lax, but it might be just my autism.
>linear algebra
Lax has never disappointed me (having greatly enjoyed his Fun Anal text), but I've never read his LA book. Hoffman and Kuntze is thrown around a lot.
If you just want a reference text, there's also the Handbook of Mathematics.
>where to go
Real Analysis(I like Royden, but I'm not sure it's a good introductory text), Complex Analysis (Kodaira is great) or Fourier Analysis.
Proper stats requires solid real anal.

Really stupid question here.
I just got an offer for a student research position AND and internship at a forensic engineering firm for my last two semesters in Mechanical Engineering.
Problem is, in order to get them, I have to agree to go into my university's masters program and get a masters in Mechanical Engineering. Not only will this put me into even more debt but I remember everyone I had talked to about job opportunities say that you don't want to get a masters straight out of uni as that will over qualify you for the jobs you'll be applying to and most of the time, a company will help you pay for a masters after you work there for a few years.
This offer is really tantalizing but I'm not sure if I should take it. I want to eventually get a masters as I want to work at a large engineering firm or an OEM so getting a masters was on my to do list anyways but I don't know if getting it right now is the best thing to do. What do y'all think?

>>11040680
Why is ten secs only 5 secs

>>11045985
appreciate it

>>11045983
Yes, a free body will always rotate around it's center of mass.

Why does /x/ feel the incessant need to raid /sci/ 24/7

Are RPN calculators comfy and worth using compared to conventional ones?
Thinking about getting a SwissMicros DM15

>>11046046
Even while *currently* applying a torque with my finger? I know it will rotate about its center of mass without any forces.

I'm trying to model a thermal expansion problem in solidworks. The object is a baking sheet, which when heated, deforms irregularly and "twists" (not sure how else to describe it). The issue is, I'm not quite sure how to constrain the model. In the actual scenario, the only constraint on the sheet is that it's sitting on a rack in the oven and has to remain in contact with the rack. Any suggestions?

is it fair to say that physics is the science of forces and chemistry is the science of substances (with atomi/molecular forces implicit here)?

>>11046072
what’s there to suggest, fellow retard?

>>11046059
it can be confusing initially, especially when trying to calculate limits, integrals and derivatives. but they are very comfy. i looked at swiss micros for awhile and currently own an hp50g and an hp15c, fwiw. now that i own these, i would never pay for a swiss micro. calculus are only useful during exams, the rest of the time the world wants you to use a full blown pc - may as well. my advice is to forgo the purchase. i got by in my classes by abusing walmart’s return policy - id buy a nice $115 calf before an exam and return it afterward for a full refund, and id advise you do the same.

>>11046058
because the male physique is a pivotal form of geometry and realization of god

>>11046017
you got an offer to buy something that you don’t nexassarily want, correct?

>>11045967
seconding spivak, but it doesn’t touch on LA and will honestly take awhile if you’re at this level. And Spivaks calc covers only single variable calc - tht other retard who replied obviously hasn’t read it completely if at all.

For a review of calc and LA I wouldn’t recommend seeing some online lecture notes and visiting practices problems. if you haven’t learned this shit before i’d recommend Spivaks calc as it’s engaging and rigors, plus some rando applies problems, then spivaks calc on manifolds and an LA book like Axler’s or Valenzuela’s’s, I didn’t like Hoffman and Kunze.

>>11046178
sorry, I WOULD recommend online notes if you’ve already learned it.

>>11045902
focus on problem solving and spaced repetition (use software here)

>>11046157
Good to know. My current calculator is a ti-36x pro and it works well, especially for complex number stuff in EE

>>11046168
I'm trying to get a research position right now. That's why I got the offer in the first place. Its just that though while I'm going to get a masters in the future, I don't know if it would be better to just do it now or wait till I can have some shitty company fork part of the bill then I can run off to a better place.

>>11046128
>I'm not quite sure how to constrain the model. In the actual scenario, the only constraint on the sheet is that it's sitting on a rack in the oven and has to remain in contact with the rack.

What solidworks constraints to use to model this situation. Or do I need a different analysis program?

>>11045983
Yes, rigid bodies will always rotate about its centre of mass (CoM). You imparting a linear motion to it won't change this fact.
To see why this is, consider rigid body dynamics as the symplectic geometry of [math]\mathbb{R}^6[/math] with a symplectic form invariant under the oriented Eucliean group [math]\mathbb{E}_+(3) \cong \mathbb{R}^3 \rtimes SO(3)[/math]. It can then be shown, from the commutation relations of the generators [math]p_i,L_i[/math] of [math]\operatorname{Lie}\mathbb{E}_+(3)[/math], that the leaves of the foliation [math]N\xrightarrow[]{\phi} \mathbb{R}^3, \qquad \phi^{-1}(x) = \frac{1}{\sum_{x_i\in V} m_i}\sum_{x_i\in V} m_i x_i = k \in\mathbb{R}[/math] are invariant under parallel transport by [math]L_i[/math], and hence the CoM does not move under rotations [math]SO(3)[/math].
>>11046072
This is unironically a very difficult problem.
First, we can model the baking sheet as the [math]x[/math]-[math]y[/math] plane in [math]\mathbb{R}^3[/math], and its first order deformation with a contact 1-form [math]\xi[/math]. Winding numbers [math]w_1(V)[/math] of the vector field [math]V[/math] dual to [math]\xi[/math] in the x-y plane can then be used to describe twisting of the sheet.
Now comes the difficult part: we can describe the thermal dependence with a parabolic PDE for the contact form [math]\xi[/math]. The form of the PDE will depend on the (perhaps local) specifics of the baking sheet, such as the temperature gradient across the tray or the presence of defects like cookie crumbs. As time [math]t[/math] evolves, the criterion for the appearance of topological defects (twists) is extremely non-trivial (related to deformations in the free energy) and case-dependent. We really cannot proceed without knowing more about the situation.
>>11046126
No.

Someone help me with intro to bio lab shit.

If the slope is positive for a spectrometer abs/time for algae shined in light, what does this mean about the change in CO2?

>>11046364
>Yes, rigid bodies will always rotate about its centre of mass (CoM). You imparting a linear motion to it won't change this fact.
>To see why this is, consider rigid body dynamics as the symplectic geometry of R6R6 with a symplectic form invariant under the oriented Eucliean group E+(3)≅R3⋊SO(3)E+(3)≅R3⋊SO(3). It can then be shown, from the commutation relations of the generators pi,Lipi,Li of LieE+(3)LieE+(3), that the leaves of the foliation NϕR3,ϕ−1(x)=1∑xi∈Vmi∑xi∈Vmixi=k∈RNϕR3,ϕ−1(x)=1∑xi∈Vmi∑xi∈Vmixi=k∈R are invariant under parallel transport by LiLi, and hence the CoM does not move under rotations SO(3)
God damn, yukarifag. None of this shit is necessary to show that.

>>11046072
Why does it twist? It is it asymmetrical?

Where do hamsters come from?

Is there any way to directly add (algebraically) two powers?
Restricting to the same base, 2^3 + 2^5 equals 40 for example, but can we represent it without calculating the values?
Basically make x^a + x^b into a single power.

>>11046681
If you could, that would invalidate the concept of a degree of a polynomial.
Considering that you'd be breaking things like unsolvability of the quintic and undecidability of general Diophantine equations, I'm inclined to say the answer is no.

What's a good place to start studying math/stat?

>>11046374
Ya

>>11046681
You could represent it in binary as 101000. Not sure how that would affect >>11046732
>unsolvability of the quintic
though

>>11045162
Does that apply to all ultramassive objects, like black holes, neutron stars, etc? Is the time dilation at the center of a neutron star roughly the same as in the vaccuum of space?

What would be the implications/consequences if string theory was proven to be right
Like how much would that change and improve things and would it lead to any practical applications

Isn't any function continuous in an interval also uniformly continuous in that interval if we choose the smallest modulus of continuity among all points in that interval?

>>11047124
In a closed, bounded interval yes.
In an open interval, i.e. (0, 1) you have immediate counterexamples like 1/x, and the same happens if it isn't bounded.
The proof essentially follows the lines you mentioned.

>>11047152
ok, thanks

Does anyone actually understand E&M? Is Griffith's really the best there is for undergrads? Any supplemental reading I can do? It really isn't clicking, and I'm just getting further behind.

>>11047267
What exactly is the issue? Maybe your math background isn't good enough for all of the multivariable calc

>>11046786
neutron star, yes
black hole, maybe

>>11040680
how to develop physical intuition w/r/t physics?

>>11047308
play catch with your pops if he eventually comes back from the store after all these years

>>11047278
I can do multivariate, as well as differential equations and linear algebra. I'm having a very hard time interpreting questions and getting them set up. Basically I don't know how to approach most problems, but once I get them set up I can do alright.

I feel I'm starting to understand this logic thing but I just need a little push
Got a brain block here

>>11047267
You can read other books but a lot of times the learning is non linear. Stop being a fag and worrying about shit like "falling behind", focusing on a deeper understanding is always more important so while you're not good at something you have to try different approaches and keep learning

>>11047364
[math]\neg S \rightarrow \neg T[math] by 2.
Then we're done.
>>11047308
Draw.

>>11047343
I agree with anon >>11047365, personally I think Griffiths is one of the better textbooks in general, maybe it just takes time to get used to it. Also visualizing problems helps a lot imo.

>>11047382
[math]\neg S \rightarrow \neg T[/math]

>>11047382
>>11047385
>Then we're done.
uhhh but the conclusion is ~T v W I don't see how it is solved

>>11047403
[math](R \wedge \neg S) \rightarrow \neg S[/math]. By 2, we have [math]\neg S \rightarrow \neg T[/math]. We stack both to get [math]\neg T[/math], and [math]\neg T \rightarrow (\neg T \vee W)[/math]

>>11043393
lmao
>suppose for contradiction...

>>11044210
answering this intuitively says that "attaching" the clock to the entangled particles probably breaks the entanglement, but really I would say that the usual quantum ontology is pretty unclear about such things as collapse and information. Read "Quantum Physics without Quantum PHilosophy" for a clearer perspective.

>>11047414
Ok I understand the end but can you just explain how you got this and the rule used
(R∧¬S)¬S

>>11047491
>how you got this
Intuition.
>rule used
"If both a and b, then a".
It's called conjunction elimination.

Can you self teach EE?

>>11044210
>that somehow knew WHEN the other was measured
found your problem

Seriously, why can’t malignant cancerous tumors just always be excised or cauterized? Even if a person has a chance of growing another one isn’t it always better to remove a tumor than let it grow and metastasize?

>>11047467
the contradiction is supposed to come from the fact that there's a finite amount of primes 1 mod 4, the hypothesis is obviously wrong but that doesn't change the fact their reasoning is also wrong

>>11047512
6002.x on Edx is basically EE 101.

>>11047565
The tumor surface is created by healthy cells, as a border wall.

Can someone tell me what's wrong with the following? Trying to find r for n = r (mod 3)
Given n^2 + 6n = 1 (mod 3)
n^2 + 6n + 9= 10 (mod 3)
(n+3)^2 = 10 (mod 3)
n+3 = sqrt(10) (mod 3)
n = sqrt(10) - 3 (mod 3)
I know the answer should be 1 but I don't know where the reasoning is wrong here.

>>11047758
>10 mod 3
>sqrt(10) mod 3
Unironically what is that goes through your head? Are you just completely insane?
Just take 10 mod 3 to get 1 mod 3 and try again.
And remember that -1 is also a root.

>>11047758
When do you ever use the fact that you are operating mod 3 classes instead of the integers?

>>11047758
>(n+3)^2 = 10 (mod 3)
>n+3 = sqrt(10) (mod 3)
LOL, not how that works

>>11047773
>>11047761
why? if = b (mod n) then a^k = b^k (mod n). Is the problem that congruence only works if simplified as low as possible?

>>11047758
Ahem, watch me.
0^2+0 = 0 mod 3
1^2+6 = 1 mod 3
2^2+12 = 2 mod 3
In essence, you should be able to look at problems and immediately determine when exhaustion is practical and piss easy.

>>11047795
*2^2+12=16 = 1 mod 3

>>11047795
and what about n>2? you haven't exhausted anything.

>>11047821
Oh no.
He genuinely hasn't understood absolutely anything about modulo classes.

Pic related is pretty good at explaining concepts and actually teaching you something. But the exercises are WAY TOO EASY, I was bad at maths in school but I remember I was able to solve way harder shit than this. Is this normal?

>>11047825
this is /sqt/, so explain why 1^2+6 = 1 mod 3 would imply that if n^2+6 = 1 mod 3 then n = 1 mod 3. Also the answer should be n mod 3 = +/-1, so how would you get that from above?

>>11047847
0^2+0 = 0 mod 3
1^2+6 = 1 mod 3
2^2+12 = 1 mod 3
You want your answer to be 1 mod 3 right? So first case is irrelevant, you only need the other 2 cases. But the first one is the answer for n = 1 mod 3, and the other is for n = 2 = -1 mod 3. There it is, your two solutions for n.
>so explain why 1^2+6 = 1 mod 3 would imply that if n^2+6 = 1 mod 3 then n = 1 mod 3
Do you understand what the elements of the mod 3 class are? Also, basically you are just asking if I check a solution for the equation indeed solves said equation, how do I know it is a solution. It isn't even the only solution, as it is shown above, but it is a solution. And so is the next case.

>>11047788
Sorry but if you can't see why jumping from a^2 = b (mod m) to a = sqrt(b) (mod m) is ridiculous and, then you just have no idea what you're doing and don't know what modulo means.
For example, it's true that 16 = 2 (mod 7). That doesn't mean that 4 = sqrt(2) (mod 7).

Optics question: If I have 2 lasers and get them overlapping, 180 degrees out of phase, and in the same direction, the waves cancel and there is no more beam, right? Where does the energy go?
Engineering question: How the fuck do you phase-control anything? Surely it's not carefully scooting one laser emitter a couple hundred nanometers back, right?

any computational biologists here?
using a generalized suffix tree, how do I compute the number of longest common substrings if there is more than one?
I understand that this would mean that there are multiple nodes with children representing suffixes of all the strings but i unno how to do that efficiently at all

>>11047938
i think i figured it out, i'll PM myself the answer

>>11047758
> Trying to find r for n = r (mod 3)
What?

>>11046364
>no
y not

To differentiate x/x+1 I rewrote as x(x+1)^-1 but can't figure it out. I use product rule now, or did this become a composite function and you need to use the chain rule? How do?

It should be 1/(x+1)^2

>>11047845
>1447 pages

>>11048913
You need to use both, often times using only one tool won't be enough to cut it, especially once you start seeing uglier functions. If you have a product with two expressions that contain the variable you are trying to differentiate with respect to (so x), it should be obvious by now that you need to use the product rule (or quotient, depending on how you wanna see it). Here you have a product of x and (x+1)^-1, hence you start with product rule:
(x)'[(x+1)^-1]+(x)[(x+1)^-1]'
To compute [(x+1)^-1]' you'll need the chain rule, although once you see it enough times you'll probably do it automatically. The gist of the chain rule is that it is used when you have a function "inside" of another function (which is NOT the same as a product or another standard algebraic operation). If you consider the functions f(x)=(x+1) and g(x)=x^-1, you'll see that (x+1)^-1 can be written as g(f(x)) (so f "inside" x, f(x) is what gets evaluated in g). Then the chain rule says that the derivative is g'(f(x))*f'(x), or:
[(x+1)^-1]'=[(-1)((x+1)^-2)]*(1)= -(x+1)^-2
And then you finish the sum, since you know both the derivatives you need
(x)'[(x+1)^-1]+(x)[(x+1)^-1]'
[(x+1)^-1]-x(x+1)^-2, after rewriting it around a little
=1/(x+1)^2

>>11047480
Cheers for the recommendation I will give it a read. When I get paid for some work I did few years back ill buy you a beer.
>>11047561
Pic related lol, only thought experiment though might have some uses in cases where you have a bandwidth of exactly 1 bit.

>>11048986
I guess it would have been easier to just do the quotient rule from the start. I saw Sal rewriting these as product rule questions on Khan Academy, but the problems on KA are nowhere near as autistic as the ones in my textbook.

does the deamination and amination of practically all the amino acids occur with transamination and involves glutamate/alpha-ketoglutarate?

>watching khan academy video
>mind drifts away
>start thinking about getting a haircut
>think back to the time a milf hairdresser pushed her huge boobs against me while cutting my hair
>realize I'm not listening to the video
>rewind 30 seconds
>repeat

The gamma function used in relativity has the expression [math]\gamma=\frac{1}{\sqrt{1-(\frac{v^2}{c^2})}}[/math]. I have two questions:
1) Philosophically, wouldn't it make more sense to write it as [math]\frac{c^2}{\sqrt{c^2-v^2}}[/math], since the "1" in the denominator has no physical interpretation?
2) And isn't the expression [math]\sqrt{a^2-b^2}[/math] technically nonsense, since the equation under the radical gives two different roots, and thus cannot give a single answer for the squareroot? Without dragging up the debate over whether [math]-1=\sqrt{1}=1[/math], doesn't this imply that the proper equation should be of the form [math]\sqrt{a^2+i2ab-b^2}[/math], or finally:
>[math]\gamma=\frac{c^2}{\sqrt{c^2+i2cv-v^2}}[/math]

>>11049178
https://www.youtube.com/playlist?list=PLF797E961509B4EB5

how do I indicate/write down/prove points of discontinuity given an arbitrary graph? take the negative and positive limit and show they aren't equal?

>>11050372
prove the contrapositive of the conditions of continuity desu

what would happen if 2 people of unbelievable strength, like 2 incredible hulks, lifted each other at the same time
would it be possible for them to float by lifting each other

>>11050839
sure I wouldn't see why not

>>11050192
Your first expression has an extra factor of c in the numerator.
In the second expression, adding 2icv inside the radical changes the value of gamma, so I'm not sure where you're pulling that from.
Not sure what you mean about the "physical significance" of the usual form, since it follows from vector algebra using the Minkowski norm

Why am I incapable of doing anything? is neuralink actually as good as they say it's going to be?

Please, for the love of God, can someone recommend me a decent pair of earplugs. I live in a hellscape of constant noise and I can't stand it anymore. I can't study like this. I can't live like this. I'm going to fucking murder somebody if this keeps up.

>>11051043
get those disposable expanding foam ones

>>11051049
I was hoping for a single decent pair that I could use longterm.

>>11051043
Get used to studying while listening to mediocre music, i.e. anime openings, or something like chiru.no
Not having a fucking desk, that's the real issue. Is studying with a notebook on your lap possible? Of course it fucking isn't.
>>11050844
Sounds about right, yeah.
>>11050166
That's why watching videos to learn doesn't fucking work. Pick up a book, sketch out the definitions, draw graphs, solve exercises and take notes.

>>11051121
I use music and white noise when I can but there are still times when it's either not loud enough to block out the noise without risking damaging my hearing or I'm working long enough that music starts to hurt my ears even at a reasonable level.

>video learning
I also prefer books, but I wouldn't say watching videos to learn doesn't work, it's that people are more prone to watching passively and not doing anything, going "well I guess I understand it" then moving on and realizing they don't understand it instead of taking notes and all those other things you suggest when utilizing books.

When I combine trig functions, does the argument have to match as well? Like if you have (3cosΘ)(3cos3Θ), you would not be able to write 9cos3Θ correct?

>>11051642
yes you're correct, they are distinct mappings.

Where did my problem go wrong?

>>11051706
find y' and y''
the 9sin^2(3Θ) part is wrong but I don't know why.

>>11040680
Why are so many tohoufags mathfags?

In the following magnetic circuit the self and mutual inductances are defined as the following. Find energy stored in the field and the developed torque

Anyone know how to do this? My textbook doesn't provide anything useful. It provides stuff on moving armatures, but nothing like this.

>>11051727
Autism

>>11042989
It's an FMA 03 vs Brotherhood situation. The new Fruits Basket anime is a one to one adaptation, so you could go with either that or the manga. Don't read the sequel manga, it sucks.

>>11051822
So the old one is no good? Think I'll read it for now.

>>11051825
It's not unwatchable, but from what I recall it had to shuffle things around and omit characters when they would've come up in the manga because they didn't have time to incorporate their particular subplots. I don't see much of a reason to watch it over the new adaptation and it's not a Hunter x Hunter situation where you might want to watch parts of both versions. The manga art is a bit rough to start, but it finds its stride soon enough. Have fun.

>>11040680
Since math and science are logical, is it possible to learn language like Japanese easily through logical methods? This whole anki grind makes me wonder if you could just back substitute somehow.

>>11051707
Last term of the first y''=... line; sin(3θ) should be sin(sin(3θ)). You made the same mistake in the first term but that doesn't matter as (-3)' is zero.

>>11051986
blessings to you

>>11051772
The total energy W stored in the magnetic field is W=I^T.L.I where I is the vector of currents and L is the inductance matrix (which is symmetric, so L21=L12). IOW, sum(I[m]*L[m,n]*I[n]).

If you change the angle, the field energy changes. Conservation of energy dictates that the total energy remains constant, so the mechanical energy supplied or obtained equals the gain or loss in field energy. The mechanical energy is the product of the change in angle and the torque, so -dW/dθ=d(Tθ)/dθ=T.

FWIW, I get W = 13.34cos(2θ)+18.75cos(θ)+25.56 mJ, T = 26.69sin(2θ)+18.75sin(θ) mNm.

>>11052033
Oops; forgot a factor of 1/2 in there. W=(1/2).I^T.L.I (which is just (1/2)LI^2 for a single inductor), so divide all those numbers by 2.

>>11050901
If that's the case, and [math]\sqrt{a^2-b^2}[/math] is valid, then taking the squareroot of a function whose roots are {1, -1}, i.e. both complex roots of [math]\sqrt{1}[/math], must be valid.
Would it also be valid to represent gamma as:
[math]\gamma=\frac{c}{\sqrt[3]{(a+b)*[a+(-\frac{1}{2}+\frac{\sqrt{3}i}{2})b]*[a+(-\frac{1}{2}-\frac{\sqrt{3}i}{2})b]}}[/math], or in other words, a cubic function with the cube roots of 1?
Or the less cluttered example:
[math]\gamma=\frac{c}{\sqrt[4]{(a+b)(a-b)(a+ib)(a-ib)}}[/math]
Or any power for that matter?

If I'm trying to determine whether there is a statistically significant difference between resting heart rate and gender, are my variables independent from each other?

Stats is not my forte. I'm guessing they're paired because they both refer to the same person's gender and heart rate? I'm so fucking confused.

>>11052360
>variables independent
Nah, you're going about it entirely the wrong way. This isn't a linear regression problem. You have two populations and you want to check if they have the same average heart rate.
>>11051727
Dunno.

So... is there any good beginner's math book? Not total beginner but also not calculus level. All I find are either too basic or shitty.

>>11052365
>same average heart rate
I'm fucking retarded. Thank you based 2hufag. So just to clarify I gotta do an independent t-test?

>>11052370
Yeah.

if there is a magnetic field originating and ending at the earth's poles, does that mean there's an electric current circulating around the equator

>>11052368
what is your math background? What do you already know? What do you want to learn?

Can someone help a retard with his lab questions?

I'm supposed to find the concentration of ASA per aspirin tablet using calibration curve and known dilutions.

From the calibration curve the concentration of ASA was 4.78 mg/L

The aspirin tablet was 0.47g

0.1 ml of the solution was diluted to 100ml.

The answer is supposed to be close to 300mg of ASA in an aspirin tablet

>In the Soviet space program, Oak was used to protect the shuttle against exhaust heat, due to it's burning properties along-the-grain.

This was in a Materials lecture. I cannot find a single source on it though.
Any help on what he's talking about?

>>11052456
>Any help on what he's talking about?
I cant source you but the way it works is the burnt wood is great heat resistant material much like aerogel.
Our cuck Scott Manley made a video about it once.

>>11052456
No idea.
Anyhow, have the exact same picture in slightly better quality and slightly smaller size.

what are the mechanics of optimizing a PNG

>>11052516
There are whole /g/ threads dedicated to that topic.
Search in the archives you are bound to ding up something.

>>11052516
Install Trimage, load up the png and optimize it.
There is further lossless trickery, but it's a real hassle.
Lossy optimization is for fags.

>>11052454
cont
the procedure

how can I find this limit?

>>11052661
Stirling formula

>>11052661
Calculate the limit of the square root.
Tip: goes to zero.

>>11052661
If x<=1 then the limit is zero. If x>1 then the sequence is divergent.

>>11052693
Are you an idiot?
[math]\frac{x^{n^2}}{n!}=(\sqrt{\frac{x^{n^2}}{n!}})^2=(\frac{x^n}{\sqrt{n!}})^2[/math].
Set x=2. The term inside the square obviously decreases for n>4.

>>11052661
Calculate the ratio of growth of both the numerator (something like x^{2n-1}) and the denominator (n, obviously).

>>11052451
I can do arithmetic and solve equations with one variable. I also know radicals and exponents.

>>11052730
read this
http://www.stitz-zeager.com/szprecalculus07042013.pdf

Can a physic fag tell me how its called when an electron falls on the nucleus? Thanks.

>>11053036
sexy time

>>11053036
capture

>>11052636
you’re fucking stupid

>>11053044
Thanks

wtf??????

>>11053179
>a hurr durr arent there more genders???

So I know this argument is false using a truth table but how can I prove it using a counterexample or equivalence transformations?
P -> Q
~P
conclusion: ~Q
I know it's very easy but am retard

>>11053223
Actually I just realized the counterexample is putting in the values false for P and true for Q. But I will probably have to learn equivalence transformations when the arguments get harder.

>>11053073
>stupid questions thread
fuck off you retard

>>11053179
>>11053223
Is this supposed to be a question? What are you trying to do? Prove that "P -> Q" isn't a tautology?

>>11053223
Write down the truth table for P, Q and P -> Q and check if any lines provide a counterexample.

why is [math]i^3 = -i[/math]

>>11053284
>can you do my work for me I promise will learn it on my own, just give me he

>>11053524
What is i times i^2?

>>11053547
beautiful, thank you

can anyone explain this circuit simplification
When a battery is ran across ab, the 20 and 10 ohm resistors are in parallel with one another which I sorta understand (but if you can explain that, it'd be great), but I don't get how their equivalent resistance (30 ohm) is in series with the 15 ohm resistor
I feel like if I could draw it I might get it but I cant even visualize it because fuck triangles
please help im about to shoot msyelf

>>11053623
>20 and 10 ohm resistors are in parallel with one another
meant series
>>11053623
>but I don't get how their equivalent resistance (30 ohm) is in series with the 15 ohm resistor
meant parallel

fuck me this shit is making me lose it

>>11051120
get a noise canceling construction set headset

>>11053554
it really isn't.

If I am differentiating using the product rule and have something like -3Asinx3x, I can just treat -3A as one term since A would be considered a constant right?

>>11053842
I'm hesitant to answer, but yes.
Please post your full solution so we can make sure you don't misuse this answer.

>>11054214
nah, no thanks. fucking asshole.

Would the Milky Way look all that different from a different planet in the galaxy?

>>11054223
nigger

Does anyone know who the person in the upper left corner is? I know John von Neumann, Grothendieck and Kaczynski but I have no clue who the last person is.

>>11053073
I promise I'm not that dumb.

I've done the calculations and I've got 478 mg per aspirin tablet. Problem is the value should be close to 300mg. I'm wondering if there was a problem with my calibration plot

Calc:

4.78 mg/L * 100/0.1 *0.1L = 478mg

>>11052368
Axler's Precalculus

>>11054223
I want it on record that if he does stupid shit it wasn't my fault.

What is the correct answer for the possible ml values? I'm having such a hard time with this electron orbitals shit. First they tell us the rule for assigning l numbers is that they range from 0 to n-1, but that's fucking wrong because certain orbitals, s orbitals for example, can only have l=0. If I answered l=2 in the problem in the pic it would be wrong even though n=3, so for the rule "0 through n-1" 1 and 2 should be possible answers, but they're not.
Then for the ml values the rule we were told in class is that ml can be -l through l including zero. But when I first answered 0 for how many possible ml values can there be for an electron in the 3s orbitals (WHICH IS L=0 LIKE IT SAYS RIGHT FUCKING THERE) it was incorrect. My answer of 5 in the pic was just a random answer I tried second.

tl;dr how the fuck many possible ml values can there be for an electron in the 3s orbital and why?

>>11055021
It's all explained in the pic, ml ranges from -l to l. The l value of an orbital is denoted by the letters s, p, d etc. and can in principle be between 0 and n-1.

However for s orbitals l is zero so ml has to be zero. I don't remember where the s p d names come from you just have to remember them.

>>11055055
God, so it's 1 then. ml can only be zero, so there is only one possible value for ml. I answered zero earlier, as in the instantiation of the only number it could be, not the number of possibilities that could be instantiated. Why did my wires cross? I'm so FUCKING STUPID

>>11055055
Kek, shit like this happens though that's why it's good to ask for help

Why does my head always ache after I study chemistry

Imagine two timelines where I’m about to press a random number generator. If I press tbe random number generator a second a later in one tineline will I get the same number?

>>11055396
Depends on your RNG algorithm and entropy sources. For most realistic scenarios today the answer is probably no.

>barely study for test
>ace it
>class struggles
I don't get it. Is the future for engineers really doomed?

>>11055344
stop inhaling the chemicals, apu

So if you have a surface and a gradient for that surface at point P, what would be a non-zero v vector in the direction of v such that the dot product of the gradient and v/|v| is equal to 0? I assume it's just the directional vector of the surface because the gradient should be orthogonal to the surface and the dot product of the two should be 0.

how do i know what grad schools i would be competitive in when applying? is it mostly guess work?

It's hot as fuck and I can't study.
Send help.

does a dotted line on the complex plane include or exclude the given limit of the range

I have no idea what a dotted line means compared to a straight line

>>11055114
This would be a vector that is tangent to a level surface/surface of constant potential (idk what brainlet mathematicians call it).

>>11056033
this makes zero sense, sorry.

>>11054214
It is a babby differential equation my textbook. I started to solve it as-is and then when the algebra became too ridiculous I looked online and found that everyone used substitution to do it instead. This is basically the last step where you plug your substituted a and b, also a' a'' b' and b''.....so it was in the step of differentiating a and b is where I was wondering, since A and B would be considered a constant.

When would it change?

>>11056126
i didn't really know what i was looking at so i made my best interpretation

basically, what's the difference between the two in my image. pretend the area is shaded and ignore the red dot

what is the term for the angle called that is on the same line of the unit circle? like pi/4 and 5pi/4 both have a tan value of 1

>>11056146
one is a function and one is a sequence

>>11056201
no, neither of them are functions or sequences

>>11052033
How did you get W = 13.34cos(2θ)+18.75cos(θ)+25.56 mJ

>>11056033
A dotted curve bounding a region in the plane means everything in the region except that curve. It's analogous to open endpoints bounding a curve.

>>11056146
It means everything inside the boundary, but not on it. E.g. if the region was the unit circle, a dotted line would mean |z|<1, a solid line would mean |z|<=1.

>>11056397
The formula for the energy stored by a system of coupled inductors (W = (1/2).I^T.L.I) should be in your course notes or textbook; that's central to the question.

From your pic related, L is [[0.002+0.003cos2θ, 0.5cosθ],[0.5cosθ,20+10cos2θ]], I is [0.75,0.05]^T, so
W = (1/2).I^T.L.I
= (1/2).(L11.i1^2+(L12+L21).i1.i2+L22.i2^2)
= (1/2).(L11.i1^2+2.L12.i1.i2+L22.i2^2)
= (1/2).((0.002+0.003cos2θ)*0.75^2+2*0.5cosθ*0.75*0.05+(20+10cos2θ)*0.05^2)
= (1/2).((0.001125+0.0016875cos2θ)+0.0375cosθ+(0.05+0.025cos2θ))
= (1/2).((0.001125+0.05)+0.0375cosθ+(0.0016875+0.025)cos2θ)
= (1/2).(0.051125+0.0375cosθ+0.0266875cos2θ)
= 0.0255625+0.01875cosθ+0.01334375cos2θ
= (25.5625+18.75cosθ+13.34375cos2θ)/1000

Re >>11052034, it seems that I already had the factor of (1/2) in the numbers but omitted it from the original equation.

what is happening in the last step? the radical just disappears from the denominator and reappears on the numerator. Are they rationalizing it? How does the other denominator expression not get changed?

>>11057821
x/√x = √x