/sqt/ - Stupid Questions Thread

Groups of atoms bind with receptors on the surface of the cell, releasing intracellular signaling molecules. For sour and salty, it's thought that H+ and Na+ ions passing though ion channels depolarize the cell directly. I don't have a very good understanding of any of these pathways though

yes

How can I calculate the velocity of a projectile in a catapult? What data do I need and how can I do it?

Atoms still have unique properties. Protons and neutrons may never actually collide but electrons can freely interact with other atoms and can even be shared amongst atoms. Within a molecule, electrons are not shared evenly, polarity is not uniform, and localized poles are created as a result, this can even affect the structure and reactivity of the molecule. Receptor binding usually doesn't involve direct bonding through sharing electrons, instead they fit together with a specific grouping of atoms out of a molecule and corresponding poles on the receptor will hold them there. Binding with the target molecule will cause the receptor to undergo structural and functional changes, which can do any number of things inside the cell

No, your inner ear gets overstimmed freaks out. More stim won't help. Also some people say it's because you've spun up the fluid in your ear, so inertia keeps it going for a while. I, however, find in hard to believe that a few mLs of fluid in a fuzzy tube has trouble keeping up with the tube.

[math] sin(cos^{-1}(x)) = \sqrt_{1-x^{2}} [/math]

Does this bring us any closer to defining sine or arccosine as a regular function?

Any topologist here who could toss a bone to a retarded sophomore? This is specifically about the "usual" topology of real numbers.

For pic related, I am trying to prove that the 3 definitions of compactness are equivalent. Specifically I am trying to prove that:

Every open cover of a set K has a finite subcover that also contains K
is equivalent to:
K is closed and bounded

At the beginning where it says assume K satisfies (i) and (ii) it means that you have to assume that K is closed and bounded, and that every sequence in K has a subsequence that converges to a number in K

The problem outlines a proof strategy you are supposed to follow but I am getting fucked in the ass by part a)

Why is it? I am sure I am missing someting big about open covers.

I just need a hint for a) and I am sure that then I can do part b)

So far I have been able to prove c) and d) (assuming a) and b). obviously)

c) follows from the nested interval property of the real numbers

d) The follows from the fact that if an open set contains a number, then it contains an epsilon-neighbourhood around that number. Then I can pick n0 so big such that the length of In0 is even smaller than epsilon and then In0 will be contained in that epsilon-neighbourhood, which is then contained in the open set. Therefore In0 is contained in a finite subcover, but also In0 is NOT contained in a finite subover (part b) ) which yields a contradiction and then QED.

So please help with part a). I need hero. I need a hero at the end of the night.

if A1 intersect K and B1 intersect K both have finite subcovers then you can build a finite subcover of I_0 by combining these two subcovers. but then this would also cover K, contradicting having no finite subcover

whoops:
if A1 intersect K and B1 intersect K both have finite subcovers then you can build a finite subcover of K by combining these two subcovers. (contradicting having no finite subcover)

Yeah, I get that. But what if only one of them has a finite subcover?

From what you said only, I cannot construct the sequence of intervals asked for in B).

For example, imagine that I0 is the smallest closed interval that can contain K. Then I bisect that and I get two "equal" parts of K.

Why couldn't I have a finite subcover of one part only?

Wait nevermind. You are a fucking genius.

You are right, both can't have finite subcovers, so at least one must need an infinite amount of open sets to cover it. And then I pick that one for my I1

then I repeat that process to get my sequence of In

FUUUUUCK.

Man you are so right and last night I was thinking about that but I got caught up in the details I mentioned in and missed the forest for the tree.

Am I going to make it? Will I ever get rid of this brainletness? Anyways, thank you my man for showing me the forest.

How can we know the number of protons in an ion's nucleus without looking at the nucleus?

If you're shaking a spring back and forth to create a certain harmonic, with the other end fixed, is it an open or closed harmonic? It looks like it's closed, but if you're moving the end back and forth, is it sort of half-open?

Because normies can't understand scientific jargon. Any scientist doing cancer research is focusing on this, but in order to get funding they have to use emotional appeals and kindergarden language.

You will need the angle of inclination, and the horizontal or maximum vertical displacement. gravitational acceleration can be assumed to be -9.81 ms^-2.

Closed at one end

Why does taking off my helmet kill me?

Couldn't I just hold my breath in space assuming my body or suit isn't damaged?

>does taking off my helmet kill me?

it would be very painful

space is fuckin cold man

Can I get a job with a pass/credit average and a great thesis and project? My uni weights a fail in such a way that it takes 2 high distinctions for it to average to a pass.

Coldness, pressure levels, radiation, you name it

How am I supposed to solve the problem in my pic? I've tried it with one and two images, both placed on the x-axis, but the calculations didn't give me the distance from the origin, or the charge.

Nevermind, I got this!

I'm supposed to find the IUPAC for that structural formula.

I got thrown off by the (CH2)4 so I thought trying to draw it out might help. Before I attempt to name it, is the line structure even correct? Should I even need to visualise the structure to be able to given an IUPAC for that structural formula?

Nvm, I did draw it wrong it's 3-ethylheptane. Sorry I can't delete that potato photo post

What are some of the best chemistry books? Intro to complex Chem.

sauce tho?

Remind me how do you calculate this infinite series?

1 + 1/2 - 1/3 + 1/4 - 1/5 + …

How long does it take your university to release exam results?
I took an exam in automata theory, and it took 3 weeks to get my results, but I think it's acceptable due to the nature of the exam (no cookie-cutter answers, the TA/professor/whoever has to check everything by hand).
Meanwhile i also had a multiple choice test in economy, and i'm still waiting for results a month later, even though it should be fairly quick to evalulate.
>Most people search "SQT" when looking for these threads.
Yeah, that's how i found this one. Didn't even notice the other one exists

-1+1/2-1/3+... = -ln(2)
1+1/2-1/3+... = 2-ln(2)

>Remind me how do you calculate this infinite series?
> 1 + 1/2 - 1/3 + 1/4 - 1/5 + …
-ln(1-x)=x+x^2/2+x^3/3+...
Substitute x=-1 and compare both series, you can see that yours is 2-ln(2).

Mass and charge measurements

I've got this problem:

1-sin^2(θ)=0.5

And I've got to find theta where -90

A little bit of complex variables:

How would I find a formula for integral over a region gamma f(az+b)dz where a,b \in (complex) and a =\ 0?

I can see it requires a change of variables but am confused how to go about it.

45, -45 you're referring to degrees. 5pi/4 would be in radians (the conversion is x*pi / 180 ).

After you convert it to radians you have to make sure it corresponds to the correct quadrant with respect to the unit circle.

Yes, +-pi/4 is correct.

Also, forgot to mention by x I am referring to the number of degrees you want to convert.

So 45 is OK if I want it in degrees? They only want it between -90 degrees and 90 degrees. I have to look up quadrants.

>1-sin^2(θ)=0.5
Yes it should be -45 and 45 (-pi/4 and pi/4)

Thanks. My powers of observation are fucking terrible, not noticing it was radians is more shameful than just not knowinghow to do it. Thanks.

All I meant by the quadrants is essentially that:

by them asking for between -90 to 90 degrees they are essentially asking for the solutions on the first and fourth quadrants.

Don't lose sleep over it though.

Oh I get it, the quadrants of a circle. Thanks.

I have a question.

Given that -90 degrees < x < 90, what is sin(60+x) = cos(x)? It also asks to use the addition formulea.

Suppose A, B and C are three sets and Cl(X) denotes the closure of X

Does Cl(A) = Cl(B) U Cl(C) imply A = B U C ?

no, just play around with some intervals and you'll get easy counterexamples

Is it possible to grow seeds on a cup full of cum?
I mean, semen has water and nutrients.

you can at least grow mushrooms

Two problems. First you would have to keep it fresh and full. Second, most of the nutrients are in proteins the plant can't break down.

So imagine you roll a 10 sided die and flip a coin. If the die doesn't come up 10, and the coin comes up heads, the die is rerolled and the coin reflipped. This increases the probability of resolving on a 10 to 55% via the equation A + B - AB = C.

My question, is this actually used for anything in real life? This is suppose to describe the chance of a temporal computer successfully extracting a solution from noise.

Fuuuck.

I wanted to use that to prove that if a set is connected, then the closure of that set is connected.

I have an easy proof for the real line, as all connected sets are intervals but I thought this proof was cheap and was really ignoring the nature of connected sets. So I want to use a proof that does not use that fact, so that the proof holds up for higher dimensions and such.

Any hints my man?

>Implying the plant doesn't have proteases

ncbi.nlm.nih.gov/pmc/articles/PMC3014533/
10 second google session.
People sure talk alot of bullshit on this board.

Is there any fuckery you can do with topology to make a tiled plane composed of regular polygons with over six sides? Like taking a hex grid and turning it into a hepta grid.

Fuckin' magnets, how do they work?

How prey tell, would you stop cells from detaching and moving around the body? Besides exising them from the tissue.

I'd say you can use the property :
X is connected iff
All continuous functions from X to {0,1} are constant, where {0,1} is the two-point space endowed with the discrete topology.

I don't "know" that property, as in I have not seen it. I am working through an introductory analysis textbook that touches on the topology of real numbers. All I "know" is the basic definition based on sequences

What exactly is your definition of a connected set ?

No, the trig functions cancel
Just express them as infinite sums like the rest of us

Pic related.

From Theorem 3.4.7 follows a really elementary proof but I want to use only the definition and the previous theorem.

Ok so you are only working on subsets of R ?

Proving your stuff without proving first that your connected set is an interval, seems very tedious, because the closure could be anything, so it's difficult to work with it. Also proving a connected set is an interval is not that hard.

>Proving your stuff without proving first that your connected set is an interval, seems very tedious, because the closure could be anything

Yeah, I think so. Maybe this book intended for the reader to go with the easy proof.

>Also proving a connected set is an interval is not that hard.

Yeah, that's theorem 3.4.7

I mean proving it from theorem 3.4.6, or even from the initial definition.

can anyone help me with binary logarithm? can't figure it out, can't find any good resource either.

lets say logbase2 of 1.6 and logbase2 of 0.6.

so its [math] 2^x = 1.6 [/math] and [math] 2^x = 0.6 [/math]

how do I figure the 'X' value?

How do you guys label potential and kinetic energy?
PE and KE?
U and K?
V and T?
something else?

U and K
And fuck outta here with R, I'm a subscript man

I got my exam back today and recieved a 70

I missed this question which I'll ask my teacher on how to do it.

The answer online I find is -1

The original question is

-1(Sec(pi/12))
——————
csc(5pi/12)

I first did converted to
1/cos
———
1/sin

Then tried flip them and use the complementary angle theroem.

I still got it completely wrong. Like way off base.

I noticed online that 5pi/12 can be converted to (pi/6)+(pi/4)

So that gives me

-1(1/cos(pi/12)) ° (2+ sqrt(2))

The question asks to use the fundamental identies and or complementary angle theroem.

What did I do wrong and how could I have fixed it?

Thanks

Does anybody know how the strength of anesthetics is measured? Like how strong is 0.4% tricaine compared to whatever dosage of morphine hospitals will give to people?

the main thing that gets you is the difference in pressure between the inside of your body and the outside.
this being said you can presumably survive a little bit of exo, maybe 20 seconds but that's a complete guess.

I am 22 and have been leading a lackadaisical, whimsical lifestyle since leaving high school. I recently visited my mother and ended up finding a few binders of schoolwork only to find that I had a little bit of trouble recalling how to solve some of the math, and had no recollection of the answers to some of the history and literary problems.

What does Veeky Forums do in its spare time to keep the mind sharp? (Aside from post on Veeky Forums.) I intend on going to a college at some point in time, but I admittedly got a little discouraged when looking at papers that were 5 years old. Idle hands and all that jazz, I suppose.

FYI: I have no inclination to be a polymath, but I wouldn't mind being well-read and knowledgeable concerning a broader sphere of subjects--typically found on a campus. Maybe half-a-mile wide and 2 feet deep, you know? Oh, and don't ask the hard questions (what do you want to be? where do you see yourself in 5 years?) because, as my father'd tell me, I still have no good answers for those questions.

Holy shit nobody's ever thought of this before

???

Maybe it was a composite of multiple photos, taken at different times, and spliced together. Or it could just be a shop, do you have the sauce

visibleearth.nasa.gov/view.php?id=57723
Yeah but I get what you're saying, I can't believe I didn't think of that.

All cancer treatments can attack metastasis. Metastasis are just the same cancer cells, but in a different place. It just so happens that at that point, most treatments aren't enough to help most patients.

Also, the body does recognize and attacks cancer cells, but they reproduce so fast the body can't get rid of it.

Also, quemotherapy basically attacks cancer cells (as well as many others). They work by being in the blood and when they pass through the tumor they are absorbed by the cancer cells.

Stupid statistics question:

For some estimate of mu (mu-hat) described as a function of 2 independent variable, how do you compute mu-hat so that one may determine the bias, variance, etc.

Eg.

mu-hat = (X[1] + 2X[3]) / 3

>and it sounds like it would be much more straightforward

What you're talking about is angiogenesis, the formation of new blood vessels from pre-existing ones. It's not simple. Like with any other macroscopic process, it has like a hundred molecular factors involved. And most of them overlap. And they have redundancies built in. And double redundancies. Imagine the most powerful firewall or whatever computer jargon you nerds use. Try cracking that.

2 = 1.6

Is the same as: log_2 1.6 = x

All we are looking at is what power we need to raise 2 to to get to 1.6. If your calculator has a log button that allows you to enter the base and the characteristic, you can plug it in an get x = 0.6780719051.

You calculator may only have a "log" button, in which case you need to change to base 10 first. Whenever you see "log" on its own with no base its always base 10 or e, in this case, 10. To do that, you change it from:

log_2 1.6 = x to log1.6/ log2 = 0.6780719051, same answer as we got before.

Likewise, log_2 0.6 = log0.6/log = -0.7369655942

Basic log rules are:

log_a a = 1
log_a 1 = 0
log_a (1/a) = -1
log_a m + log_a n = log_a mn
log_a m - log_a n = log_a (m/n)
log_a x^n = nlog_a x

I live in California. Should I be worried about sushi in the wake of Fukushima?

Can someone PLEASE show me actual math behind this as opposed to y is sin x is cos viola equation is 2y-3x=2

how were you introduced to polar co-ordinates?

this problem is just showing that not everything is already in a nice form for you

[math]\sin{\theta}=\frac{opp}{hyp}=\frac{y}{x^2+y^2}[/math], also [math]\cos{\theta}=\frac{adj}{hyp}=\frac{x}{x^2+y^2}[/math], finally [math]r=x^2+y^2[/math].

substitute those in and cancel out [math]x^2+y^2[/math] to get c.

sorry i missed the square roots around all my [math]x^2+y^2[/math], pythagoras theorem

someone please explain what [math]mathbb{R} / mathbb{Q} = \{ x+mathbb{Q} \textbar x \in mathbb{R} \} [/math] is structurally

someone please explain what [math] \mathbb{R} / \mathbb{Q} = \{ x+ \mathbb{Q} \mid x \in \mathbb{R} \} [/math] is structurally

An uncountable, abelian group

did you make a mistake or do I just not understand your notation?

that looks like the reals factored by the rationals

if it is, then examples of elements are [0], [e], [pi]

If you shoot a gun into the air at a 85 degree+ angle, when the bullet comes back down can it kill somebody?

What's mathematical modeling? Is an equation like pv=nrt or f=ma a model?

Is EE the best engineering major for a math fag?

Because the real world works on making a buck and prevention is bad for existing business.