Archived threads in /sci/ - Science & Math - 176. page
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I've always heard that where you do undergrad doesn't matter that much if you're gonna go on to do your master's, but you need to go to a good school for your master's.
I just applied for grad school and got into Boston U with a weak GPA and terrible GRE scores. I got in with a scholarship.
A couple of my dumb ass friends who have mediocre GPAs also just got in... to Columbia and Johns Hopkins.
This was pretty amazing to me. BU's acceptance rate is 34%, and Columbia's is 7%...
but then I found out the grad school rankings....
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>>8047553
Universities are businesses.
Businesses like money.
You have all these retards just dying to give you money
So you take their money.
You distract with a couple of fetch quests and at the end of it you give them a piece of paper
Somehow the retards feel satisfied
Profit percentage: 100000000%
>paying for grad school
>>8047637
most everyone I know does, except a BRILLIANT physicist roommate who got a full-ride to Rochester, and some creative writing MFAs
Calculating everything out, after the program I'll be ~$50K in the hole after grad school, and all the people I know who went to grad school laugh because apparently that's less than half of what most any of them owe.
I need help /sci/. This was in my math professors room, the previous occupant of the room put it up and no one has been able to figure it out. It says something in the center, and has a key around the outside to decrypt it. Help me?
Anybody?
Each patch corresponds to a letter, the key is along the border, with a-z in order. But you need to reflect it in a mirror to get the final answer.
So the bottom right square would be the first letter? Or the
Top right?
I need to open the window in my room occasionally for some fresh air. However during summer there are bugs outside. We all know the odds of bugs entering my room while the window is open is proportional to the time my window is kept open and how far it is open.
For the sake of getting as much fresh air as possible while keeping as many bugs out, should I open my window very far for a short time or open it just a little for a long time?
Just buy a bug net you dummy
>>8047466
Incoming Goldman start intern here. Just ran the numbers on my window model and it concluded that you should keep your window open wide for a short amount of time
>>8047466
Dumb makiposter. What about a net?
where are the trigonometric functions derived from, how the hell did someone think of creating sin/tan/cos (arc funcs too)
thanks, non pic related
I don't know the history of trigo functions, but I can tell you that , nowadays, the formal definitions of sine, cosine, tan... are infinte sums based on the Taylor series of the functions (aka sum of polynomials).
Sine in spanish is "seno" which means "boob" and the greek letter "theta" pronounced in spanish is "teta" that also means "boob" so, if you say "sine of theta" you are saying "boob of boob". wew.
Speaking of which, since the question's answered, are there any geniuses here who wouldn't mind getting paid to take care of some work for me?
sorry for being a maths noob but are the sin/cos/tan functions derived from the taylor series then? if not where from, where do they come from, how where they founded
Explain to me how your life will ever be better than that of Dr. Brian May.
>> You can't
simple. i dont like curls.
imagine trying to comb that mess
pass
That's Sir Dr. Brian May to you, pleb.
Is this expression for the efficiency of a fan blade correct?
I'm making a ducted fan and seeing as these things take a long time to draw and a lot of money to manufacture I want to have some idea of the efficiency even if it's basic. I'm worried because it's a 12 blade fan which means the blade angles have to be quite steep in order for it to all fit together. Other EDF manufacturers seem to have done the same thing and theirs works fine but I want to check anyway because mine is much bigger.
If pic related is right then I can compute the...
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the page with the final answer
If /sci/ helps me out I'll post a video of it in operation. It's gonna sound amazing. Might rice it out as well with supersonic swept back blades and afterburners
Oh come on seriously fuck this board, Loads of people eager to spew bullshit about quantum mechanics or inter universal teichmuller theory but these same people somehow don't know enough physics to verify a simple efficiency expression? I'd use physicsforums if I was good at LateX.
Hello /sci/ i figured this would be the best place to get some insight to something I thought about just now.
I just came off watching an episode of Big Bang Theory (yeah yeah i enjoy the show so hold your laughter for later) and the characters are musing about the problems they have with their new invention being adapted by the military to improve their systems. This isn't the first time I have heard about the internal crisis faced by well meaning scientists when they see their invention co-opted for use either as a weapon or a part of a weaponized system, especially...
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>>8047288
>I just came off watching an episode of Big Bang Theory
stopped reading right there
>>8047288
>Big Bang Theory
End it already.
Question Time. Astrophysics related.
My friends and I have had a discussion and cannot think of a solution.
If a large object, e.g. the size of the moon but completely hollow is orbiting an even bigger object e.g the earth (Tidally locked) and there was a very small object, e.g. a pencil at the center of this hollow bodied moon what would the pencil do?
Would it remain at the center of the 'moon' or slowly gravitate towards the sides?
>>8047173
The pencil would feel no gravitational force from the hollow body that it's inside - https://en.wikipedia.org/wiki/Shell_theorem
The pencil would only feel a gravitational force from the earth, and would stay orbiting in the centre of the moon.
>>8047173
By Gauss' law gravitational force at a point a distance r away from the centre of this sphere is only dependent on the amount of mass enclosed by the sphere of radius r. That is to say, if you have no mass inside if the sphere then the gravitational field inside of it will be 0.
So the pencil remains where it is, regardless of if it is at the centre or anywhere else inside the moon.
>>8047173
The pencil wouldn't feel any gravitational effects from the hollow moon but it would feel centrifugal forces on it. It would move to the back of the moon on the far side away from the planet.
How does math work?
This shit is fucking voodoo magic. Especially complex numbers.
Elegant right?
>>8047145
I stopped caring about math when I was introduced to the concept of imaginary numbers. What a crock of shit. If your equation can only be solved by inventing numbers that can't exist, like some kind of math deity , then you are fucking wrong and the math is flawed. Same for algebra solutions that basically say "the correct answer is whatever the correct answer is". Thats what the math said transcribed to words but god forbid if i wrote in down in english instead of the ancient math runes the teacher...
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>>8047386
pls be troll
A person wants to attach a variable resistor/potentiometer to an appliance with power output of “P” to dim it’s light, what is the maximum power to be used by the variable resistor in terms of "P"?
HINT: the answer is independent of the voltage
Have fun!
>>8047065
No.
Isn't it P/2
If we reduce the appliance to a Thevenin equivalent, power consumption across the load resistor occurs when the variable resistor equals the source, so equal power loss over both means P/2
I'm just a chemistry student so I may not remember my circuits right
Just wondering...
i saw a show on discovery with morgan freeman that said black people avg lower iqs than whites and asians and jews avg higher than whites...
I think the butthurt shockwave will be detectable by the nearest solar system that is home to tech advanced aliens.
> are we allowed to talk psychology/psychometrics here yet?
You can talk whatever you wanna talk about.
>>8047039
What show? I wanna see!
>>8047039
Psychometrics is politically incorrect.
Isit possible to teach yourself physics? I left highschool with little knowledge in physics, i really liked it but i couldnt pick it because of the teacher that taught it.
>>8046986
I started learning physics and math after high school because I wanted to build myself a video game with a physics engine. (At that time there were no physics engines like ageia, box2d or ODE to download from the internet). Had to learn everything from scratch, newtonian physics, matrices, quaternions, tensors etc. It's possible but you will need some dedication. Today I understand most relativistic physics and even some quantum mechanical notations. I'm not professionally taught. But I'm very proud...
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>>8046986
You can, but it won't very easy. You gotta push through it lad.
Definitely although you might find it more difficult to motivate your study since you aren't paying tens of thousands of dollars to have people tell you what to do.
Depending on how far you want to go, it might be better if you learnt mathematics to a intermediate level first.
What do you think are the best pathways when learning algebra?
When I took a course we basically went straight for Galois theory ASAP (which I heard is unusual). There are so many different ways you can take algebra, so I want to hear what /sci/ did or what you'd recommend.
My undergrad went
1 Intro linear algebra
2 Rings and fields (baby Hungerford), more linear algebra (Axler)
3 Group theory (Armstrong), reflection groups (Humphreys), Galois theory
4 Algebra (Dummit/Foote), Commutative/homological (Eisenbud/Matsumura/etc.), Representation theory (Vinberg)
I think I turned out all right, I think groups could have come earlier though
>>8046981
Are these separate courses?
>>8046982
Yes, with the textbooks used for each one
I probably took an above average number of algebra classes
Could you make a magnetic field so strong it deflects stops, or slows down bullets to the point they are no longer a threat? What other effects would this kind of field have and how much power would it take?
>>8046844
Since bullets are generally made of lead, no
>>8046848
arent all materials at least a bit conductive, i mean isnt there an amoun tof electric charge that will repel it?
>>8046873
No, fuck you
![Battery-Life-charge-tips_thumb800[1].jpg](https://i.imgur.com/XmsrwAV.jpg "Battery-Life-charge-tips_thumb800[1].jpg")
I've heard from many people that battery technology is advancing exponentially and we're increasing battery durability times and times more compared to previous years. Is there any truth behind this ?
Nope. None at all. Battery technology is advancing, jusf not exponentially.
>>8046840
Battery development is pretty slow, hard work right now. It's unlikely we're going to see any large jumps in performance any time soon.
>>8046840
Really? I've heard battery time is increasing logarithmically and will slow down significantly in a couple decades if new technologies aren't developed.
