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Archived threads in /sci/ - Science & Math - 306. page
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File: mercury.jpg (19 KB, 325x325) Image search: [iqdb] [SauceNao] [Google]
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Friends! Reminding you once more there will be a transit of Mercury across the sun TOMORROW, May 9th. This event lasts 7 1/2 hours beginning at 7:12 A.M. Eastern time. The last time this occurred was 2006 and it won't happen again until Nov. 2019.

A telescope with at least 60x magnification, and a solar filter over it is the ideal way to view the event, though there will be many observatories showing live streams. One of such can be found here: http://main.slooh.com/event/transit-of-mercury/
>>
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Western Europe, Eastern North America, and much of South America can see the entire transit. Most of the rest of the world may catch at least part of the event. Australia & east Asia is boned.
>>
>> Implying I'm going to wake up at 7 am to see a fucking transit
>> What kind of astrophysicist am I
>>
>>8059279
I understand that's actually sadly common, for astrophysics or astronomy students to never once go out and actually look at the sky.

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When do you think first contact will take place? What do you think about the great "roar" Which is blocking out signals or the object which follows earth? Post your thoughts! :)
>>
>>8059117
Fuckoff and die.
>>
Never
Never
Never
>>
Heard of black knight satelite?

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I can't think of a better board to ask on
>>
>>8059107
u wot
>>
I'm not certain, but I think emotion and sensation are other parts in the brain. They are linked but not in the same place, so I guess you can have sensation without emotion if you cut that connection.
>>
>>8059107
hunger, pain, temperature, thirst and such are sensations aren't they?

I guess even a very emotionless person can still feel hunger, pain and etc.

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We could devolve back into monkeys if we tried or evolution is an one way street?
>>
>>8059073
technically that is an ape
>>
>>8059078
Apes are a special case of monkeys.
>>
>>8059073
>Devolve
Learn what evolution is before shit posting about it on /sci/
Long answer is that we can technically a tempt to fuck up our genetics intentionally so we get a fucked up baby but that's illigal and stupid anyways.

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How would you find out the angular velocity of a wind turbine only knowing the RPM and wind speed?
>>
>>8059040
waaaaaait a second, is this homework?
>>
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>>8059046
Theres a wind turbine right over there see? I took a picture of it.
>>
wind speed right now is 13 mph
so 5.811 m/s
and it's spinning at about 65 RPM

so angular velocity must be...

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The function
$f: \{ 0,1,2,3 \} \to \{6,7\}$
defined by
$f(0):=6$
$f(1):=6$
$f(2):=7$
$f(3):=6$
is surjective: Its range (the set of values, 6 and 7) indeed equals its codomain ($\{6,7\}$).

The function has a right inverse
$r: \{6,7\} \to \{ 0,1,2,3 \}$
For example,
$r(6):=3$
$r(7):=2$
makes it so that $f \circ r$ is the identity function on $\{6,7\}$:
$f(r(6))=f(3)=6$
$f(r(7))=f(2)=7$
It's...
>>
>does every surjective function have a right inverse
Yes, this is the definition of surjectivity.
>>
>>8059014

https://proofwiki.org/wiki/Surjection_iff_Right_Inverse
>>
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>>8059022
That proof uses the axiom of choice.
So I take it you say the axiom of choice is true?

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Explain this, /sci/

I am dumb but I think simple logic proves airfoils are designed upside down.

The curved surface on the top would displace more air, creating a higher pressure than the flat surface on the bottom. This means that the lower pressure area on the bottom of the foil would suck the aircraft downwards, instead of upwards.

Am I just stupid? I don't get this at all. Please help. Assume the angle of attack is totally flat and the flat foil is totally flat also.
>>
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In this picture it's perfectly clear that the top surface has a greater surface area than the bottom, meaning it displaces more atoms and would have greater pressure on it....

Right?
>>
>>8058957
>Assume the angle of attack is totally flat
That's not how wings work, senpai.
>>
>>8058957
It's dynamic pressure, and since sum of dynamic and static pressure in.given area is constant, static pressure is pulling the wing from above and pushing from below.

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I have my AP Physics C: Mechanics exam tomorrow.

Any tips? This is the second year they're allowing calculators on MC, so I'm not sure how the multiple choice is going to be compared to released exams.

>also, predictions for FRQ topics?
>>
>allowing graphic calculators for past exams
>ban graphic calculators three years ago
>make exam questions harder

Fuck my life.
>>
>>8058893
Oh, so will exams pre-2012 be like exam in 2016?
>>
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I'm an ap physics teacher, feel free to ask me specific questions. Yes I'm also on 4chan on a sunday morning; I'm good at physics not at life.

Always be sure to explicitly cite conservation laws when doing an FRQ. It's very often something that is specifically laid out in the point distribution. Same with units and an initial set up.

Remember the AP scoring guidelines are pretty forgiving (just setting up and attacking a problem is often the majority of the points) and additive (you can put wrong stuff and it's basically never penalized,...

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What does division mean in probability?

If I understand correctly, then when translated from math to English:

$P(A)*P(B)$
becomes
>the probability that A and B are true

$P(A)+P(B)$
becomes
>the probability that A or B is true

$P(A)/P(B)$
becomes
>???

If it doesn't "mean" anything in particular, then is there at least a metaphor that would help me imagine it better?
>>
>>8058839
>If I understand correctly
you don't
>>
>>8058839
I always think of it as disregarding redundant cases.
>>
>>8058839
>A 'if' B.

If you don't understand it just apply whatever variables you have to Bayes's theorem and it'll work.

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How can a poor educated 20 year old get into MIT?

I have no money but access to a computer with internet.(i live in europe)

Lets assume i am not a brainlet.
>>
Study
>>
>>8058663
This. What did you expect OP? A person will just notice your non-brainletness and invite you to MIT?
>>
>>8058670
>>8058663

I assumed that,i just mean like, would i have to send them a letter? will my european grades be worth something? how can i prove my non brainletness to them?
how do universities decide on what students to accept? should i go to uni in my country , try to be exceptional here first?

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Debate everything related to:
-Terrafoming planets
-Eath-like exoplanets
-Space habitats/colonies
Will the humans be able to do all of this? Which is the best candidate for a human colony, Venus, the Moon or an Space Habitat?
>>
wouldn't it be easier to just mine planets for resources and then live in artificial environments, ie space stations?

isnt transforming an entire planet to meet your physiological needs rather than creating your needs in an isolated area really inefficient?
>>
>>8058559
I've always thought about space colonization like this. I guess it's about cost effectiveness

Would it be cheaper to: a) continually move the resources out of the influence of the planet to the station/next planet. or b) terraform the planet and use the resources there.
>>
>>8058545
So far Photshop and blue/green colours in the palette are the most sofisticated terraforming tools we have.

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So it turns out I've been wrong about this. All that philosophical talk about "is it really me anymore if all my cells are replaced" is just useless.
>>
>>8058458

Sage
>>
>>8058458
I understood that was bullshit since first time I heard it in elementary school. Who even belived that?
>>
>>8058458
Why does it render that question useless?

I am currently making my project for my fucking liberal arts class pertaining to Abundance and Need.
I decided to tackle the topic of the world's food shortage and the solution I came up with is "The use of Artificial Islands for agriculture and it's effect on the world." A bit wordy, I know. I also have to do this myself because two of my teams members can barely speak English (Still love 'em though), and some girl that never responds to my texts or comes to class.

The...
>>
>>8058314
>some girl that never responds to my texts or comes to class

I fucking hate this type of girl, and then whenever she does show up she "has to leave early". Fuck you.
>>
Okay, what kind of islands? Like those airports in Asia / China but for farming? Floating things as in a frame and then soil on top?

How feasable is this? I suppose such an islands incurs huge investments.

What about maintenance? Water and nutrient recycling, soil conservation..
>>
>>8058319
Yeah, last thing she said to me was "I can't meet, I have a meeting."
Never said if she did the worksheet and she never sent me any sources that she was supposed to research and summarize.
>>8058320
I was thinking along the Dubai mindset. Redistribute sediment onto coastlines or raised areas in the sea to support the island.
Feasibility? Probably fucking non. I'm estimating 6 billion in costs for the project. But hey, hypothetical solutions.
Didn't...

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I don't fully understand IBM's quantum computer stuff. Am I a brainlet?
>>
Very simply, normal computers work, either there's power going through a wire, or not. It's 1, or a 0, they're binary systems. What quantum states allow for is much more complex information to be encoded into a single bit.
>>
>>8058281

sounds dumb

>complex information encoded into a single bit

then it wouldn't be a single bit
>>
>>8058285
Regular computer bit is either a 1 or a 0, on or off. A quantum state can be much more complex than that, because as we know things can be both particle and wave at the same time and the uncertainty about quantum states allows us to encode more information into a much smaller computer. So that's what's exciting about quantum computers.

Don't get me going on this, I'll be here all day, trust me.

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Any chemistry fag here? My fucking teacher mailed us an assignment over mail due to tomorrow. I don't have my books with me so I'm pretty much fucked. Can someone help me to name the organics bellow? Dutch fag here so english isn't that good.

>>
You deserve to fail if you are not able to check on the various internet pages how to apply the organic nomenclature.
>>
>>8058236

>H3C
>not CH3
>>
>>8058236
3-ethyl-2,4dimethylhexane

hexanoic acid

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Hello /sci/. Math noob here that's starting trig next semester.Did anyone struggle with trigonometry? Do you still have the unit circle memorized after all the years since you were in it? Its very different than basic algebra(just got an A in college algebra). What are the best ways of mastering trigonometry? Tips, tricks, best text books etc? Thank you!
>>
I'm halfway through a trig class right now, in what's probably the worst format possible: online course with no homework. Instructor posts lecture notes every week, gives us a weekly six-to-ten-question quiz, then a midterm and a final. Pretty much like teaching yourself trig from a textbook.

So I may be having a harder time with it than is usual. I'd say so far the really challenging parts were the first two or three weeks, when you're still wrapping your head around the basic concepts. After that it starts to feel more comfortable.

But then, I haven't finished yet. Might be speaking too soon.
>>
As far as tips, before the start of the term, make sure you really understand translating and inverting functions- that will probably come up on, like, week 2.

Also, don't just look at a picture of a unit circle when you need to reference one; draw your own. That will help you commit it to memory faster.

Last thing: Khan Academy is great for trig. I've been pretty much entirely relying on it.
>>
>>8058049
Memorize the unit circle, there's a pattern to it that's easily remembered once you get the hang of it. There's obviously more to mastering it, but that's a good start.

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Deep web, does the mariana deep web really exist?
Also what is a closed shell system and can you really access Teslas experiments?
>>
>fell for the meme
That pic is a troll image
>>
where's that one image that goes through the layers and explains why it's bullshit
also >>>/x/
>>
>>8057965
can you find me that pic please bro

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reminder: if you're not mathematically modelling what you're studying you're doing it wrong.

why does the scientific method excuse such sloppiness? i'm sorry but writing your opinions in a diary isn't worth the paper it's printed on.
>>
itt: mathfags with a superiority irrational
>>
>>8057887
>t. diary keeper
>>
>>8057882
writing your opinions on 4chan isn't worth the bytes its saved on.

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So, I'm a an ugly guy in my 20s. I'm quite frustrated because I'm judged by my facial structure.

What I wanted to ask you is, do you think there is a possibility that in the future there will exist more means of improving one's face beyond plastic surgery, that would be able to turn someone's ugly face into an attractive one? Current capabilities of plastic surgery can't do that as we all know, you just end up looking worse, a freak. Please help me out on this one!
>>
>>
>>8057889
Nop OP, but I've tried that.
Didn't really help.

Celebrity I resemble the most?
goddamn Stephen King, FML
>>
>>8057881
like a buttload of problems in life this can be solved with tissue engineering.

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How do we reach faster than light travel, whether it'd be traveling across the Sol System, to sailing across the galaxy? How do we do all this without the negative effects of time dilation?
>>
>>8057785
become lighter than light

>>
There is no way to travel faster than light itself, however a shortcut in space such as a wormhole can make it seem like you travel faster than light. Since you are taking a shortcut you will reach your destination far before light can do so (not counting the light that moves also through the wormhole). This is still not travelling faster than light but just reaching your destiny before light does.
>>
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>>8057785
>>8046456

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Hey /sci/, why aren't you into Kerbal Space Program yet?
>>
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>>8057664
>Not Orbiter
>>
>>8057669
Poor cows, they can't handle the future.
>>
>playing a shit game by retarded mexicans that hasn't changed significantly in nearly 3 years
epic

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If I say $f:A \rightarrow B$ , f maps from A to B, is A the codomain or the preimage?

Given that $f:A \rightarrow B$ , are there elements $a$ of $A$ for which $f(a)$ does not exist in $B$ or aren't there?
>>
>>8057602
*last question should ask "can there be" not "are there."
>>
>>8057614
So the codomain of a relation equals the pre-image?
>>
>>8057602

Both, but you prob mean codomain
And no there can't.

Say you had some subset $C \subset B$
Then the pre-image of f restricted to C is the subset of A $\{ x\in A : f(x) \in C \}$

That's how I understand it

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I think I get the concept of "hypercube", but I can't completely understand it or mentally visualize it mentally.

Can you?
>>
>>8057591
>mentally visualize it mentally
Oh gawd, forgive me anons.
>>
>>8057591
yes, I can
>>
>>8057591
>Can you?
yes. if you can't, then either you don't understand what 'visualization' means in dimensions greater than 3, or you don't understand the 'concept'.

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So /sci/ how did you pay for college? Just graduated and I'm wondering how it gonna pay for it.
>>
>>8057537

don't have poor parents
>>
>>8057537
Student loan, help from family, part time job

How else do you think anyone pays for anything?
>>
>>8057537
hack
banks

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>accidentally make manganese heptoxide
>it was in an organic solution
>hand gets coated with manganese dioxide
>>
>>8057406
>>
>>8057406
You can get free welfare now!
>>
have you noticed a change in your penis size ?

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I always wondered how jet engine work. Maybe that is obviously but I don't understand.
Pressure distribute in all directions with the same force. Why turbine rotate compressor and not otherwise or in another words why it rotates and air flow in one direction whet it press whit the same force in both?
>>
>>8057382
>why it rotates and air flow in one direction whet it press whit the same force in both?

Because engineers did like 500 different engines and then 1 actually worked and they have just spent the last hundred years making it better and better.
>>
>>8057382
Work on your fucking prose, Pajeet.
>>
>>8057382
This might help?
I can't tell what you're asking

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Shitty physcist here.

How do I learn to sketch graphs?

for example, how would you know that y=sinx/x looked like pic related?
>>
The main things that characterise graphs are axis intercepts and the turning points.
>>
>>8057375
Well, first you know its probably sinusoidal. Then, think of the graph of 1/x. Try plotting them together.
>>
What is the value of y at x=0?

Why don't we have space portals yet, /sci/?
>>
>>8057363
If it's so easy why don't you make one?
>>
Exotic particle quantum tunneling yachting quarks
>>
>>8057363
Because we don't have a way to make arbitrary amounts of negative energy

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ITT: God tier pure math books
>>
>>8057200
Best book on Complex AG here. Screw G&H.
>>
This is a pretty good resource for textbook recommendations

http://math-blog.com/mathematics-books/
>>
Anyone know a good cell bio textbook? Sick of MoBio of the Cell's inane bullshit. The only good chapters are the ones on microscopy and organelles.

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Where are all the 40+ year old people in tech?
>>
Dang, ment to post it on /g/ not on this shit board
>>
>>8056993
kys
>>
>>8056993
Jessica JUSTain

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