## Search found 79 matches

- Tue Jul 19, 2011 8:13 pm UTC
- Forum: Mathematics
- Topic: Chaos pendulum
- Replies:
**19** - Views:
**4274**

### Re: Chaos pendulum

I have a strong feeling the OP is trying to get us to complete an assignment/presentation for him.... We don't do your homework for you here...

- Mon May 30, 2011 7:39 pm UTC
- Forum: Science
- Topic: Combustion catalyzed fusion
- Replies:
**14** - Views:
**2229**

### Re: Combustion catalyzed fusion

The energy that would be required to produce a magnetic field of that magnitude to create pressure high enough to create fusion would exceed the energy output of your fusion reaction by A LOT.

In other words, maybe it's possible, but it's not at all efficient.

In other words, maybe it's possible, but it's not at all efficient.

- Thu May 26, 2011 4:00 pm UTC
- Forum: Science
- Topic: Could time be measured in meters?
- Replies:
**83** - Views:
**11717**

### Re: Could time be measured in meters?

There are books out there on general relativity (and other topics mind you) that use a different naming and notation convention than in typical introductory textbooks on physics. I have a very hard time believing that any physics textbook would treat distance and time in the same units using any co...

- Thu May 26, 2011 1:57 pm UTC
- Forum: Science
- Topic: Could time be measured in meters?
- Replies:
**83** - Views:
**11717**

### Re: Could time be measured in meters?

That conversion only makes sense if you're referring to the speed of light and the distance it travels in 'x' seconds (or minutes, hours, days, years, etc.). There are books out there on general relativity (and other topics mind you) that use a different naming and notation convention than in typica...

- Tue May 24, 2011 5:35 pm UTC
- Forum: Mathematics
- Topic: Need help with Gaussian Elimination
- Replies:
**8** - Views:
**1285**

### Re: Need help with Gaussian Elimination

At your stage in the course there really isn't much use to LU and LDV factorization. However, if you continue on in linear algebra you'll find that they get really helpful at time in identifying symmetric matrices, finding the quadratic form of an equation, and as already mentioned operation countin...

- Mon May 09, 2011 5:06 pm UTC
- Forum: Science
- Topic: Quantum Entanglement
- Replies:
**39** - Views:
**6540**

### Re: Quantum Entanglement

... In the MWI, on the other hand, there's no faster-than-light communication. The electron doesn't change state when we measure it, it was *always* spin up (or spin down). However, there was a very closely related world with the opposite orientation that caused interference, preventing us from mea...

- Wed May 04, 2011 6:05 pm UTC
- Forum: Science
- Topic: Quantum Entanglement
- Replies:
**39** - Views:
**6540**

### Re: Quantum Entanglement

Yeah, the idea that the electrons have a specific spin before we open the box is called a hidden-variable theory and is entirely wrong . Not really what I was referring to with my posts. I was trying to get him to realize the subtle mechanics behind entanglement. I guess I failed with my descriptio...

- Wed May 04, 2011 3:06 pm UTC
- Forum: Science
- Topic: Quantum Entanglement
- Replies:
**39** - Views:
**6540**

### Re: Quantum Entanglement

It's still a 50/50 statistical thing, either the particle is in one state or the other. We have no way of knowing until we observe it. What I'm trying to say is that the electrons are already in one of those states, but until we observe the particle and 'collapse' it's wave function we have no way o...

- Wed May 04, 2011 2:56 pm UTC
- Forum: Science
- Topic: Quantum Entanglement
- Replies:
**39** - Views:
**6540**

### Re: Quantum Entanglement

The electrons are entangled whether someone is looking at them or not. Even without observation one will be spin up, the other will be spin down but there is no way of us knowing which is which until we observe them. Opening the box collapses what WE see to either spin up or spin down, but the elect...

- Mon May 02, 2011 4:41 pm UTC
- Forum: Science
- Topic: Quantum Spin?
- Replies:
**16** - Views:
**2454**

### Re: Quantum Spin?

There's a reason most professors begin teaching Introduction to Quantum Mechanics by telling you not to think about the electron as a particle, but to think of it as a wave. When you think of it as a physical particle, a billiard ball per se, you get into these visualization issues when trying to cr...

- Fri Apr 22, 2011 10:30 pm UTC
- Forum: Science
- Topic: God Particle?
- Replies:
**12** - Views:
**2248**

### Re: God Particle?

That would be the Higgs boson. It's a rare form of matter, and it is thought to possibly be related to dark matter, which is something astrophysicists made up to explain why their models of the universe don't work correctly. Astrophysicists came up with the idea of Dark Matter and Dark Energy in or...

- Sat Apr 02, 2011 7:28 pm UTC
- Forum: Science
- Topic: Physics for a Mathematician...
- Replies:
**2** - Views:
**870**

### Re: naturall Philoſophie for a spelling...

Stupid word filters, so you're a mathematics major wanting to study theoretical physics Best I can suggest to get into it a little is Roger Penrose' The Road to Reality. He begins with a very mathematical standpoint on hypersurfaces and hyperfunctions and segways into general relativity. He covers p...

- Sun Mar 27, 2011 1:24 am UTC
- Forum: Mathematics
- Topic: Ever felt "off your game" mathematically?
- Replies:
**15** - Views:
**2633**

### Re: Ever felt "off your game" mathematically?

The more advanced stuff I learn the less confident I get with BASIC mathematics... If the topic is something I'm currently studying I usually feel pretty good about it... but if it's high school stuff I fail miserably... While talking to the rental agent at an apartment I'm looking at I asked how ma...

- Fri Mar 04, 2011 5:00 pm UTC
- Forum: Science
- Topic: Laser Tractor Beam soon? ZOMG!
- Replies:
**5** - Views:
**1298**

### Laser Tractor Beam soon? ZOMG!

http://blogs.discovermagazine.com/80beats/2011/03/03/how-to-build-a-laser-tractor-beam-in-theory/?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+80beats+%2880beats%29 So cool. Though it's still just a simple theory I think it's remarkable that there is even a theoretical possibil...

- Thu Jan 27, 2011 5:19 am UTC
- Forum: Science
- Topic: easy physics problem.....
- Replies:
**3** - Views:
**2372**

### Re: easy physics problem.....

Create a mock-free body diagram for the velocities. One vector east with the appropriate wind speed. Another vector north for the final velocity north. Now what is the required velocity vector required to cancel out the eastern wind and result in the pilot travelling north

- Sat Jan 15, 2011 10:10 pm UTC
- Forum: Science
- Topic: I just found the velocity of.. something..
- Replies:
**7** - Views:
**1449**

### Re: I just found the velocity of.. something..

Looks like the tangential component of velocity.

edit - and btw there's no need to change vdt to dx:

[math]P_{avg} = \frac{1}{\Delta{t}}\int{Fvdt} = \frac{1}{\Delta{t}}Fv\Delta{t}[/math]

[math]\frac{P_{avg}}{F} = v[/math]

edit - and btw there's no need to change vdt to dx:

[math]P_{avg} = \frac{1}{\Delta{t}}\int{Fvdt} = \frac{1}{\Delta{t}}Fv\Delta{t}[/math]

[math]\frac{P_{avg}}{F} = v[/math]

- Tue Jan 11, 2011 12:23 am UTC
- Forum: Science
- Topic: Undergraduate physics in a book?
- Replies:
**7** - Views:
**2036**

### Re: Undergraduate physics in a book?

Haven't personally read Penrose's book, but the reviews I just read seem to say it's a difficult one to read for someone with no significant physics/math backround... in other words: good luck. I should also recommend The Feynman Lectures on Physics, I personally love them and they're a great refere...

- Sun Jan 09, 2011 11:46 pm UTC
- Forum: Mathematics
- Topic: Math Problem Help (flying fish trajectory)
- Replies:
**6** - Views:
**1870**

### Re: Math Problem Help (flying fish trajectory)

Graphed it using matlab... looks pretty good to me, why do you feel like it's the wrong answer??

- Sat Jan 08, 2011 9:49 pm UTC
- Forum: Mathematics
- Topic: Taylor series remainder in integral form
- Replies:
**1** - Views:
**1352**

### Re: Taylor series remainder in integral form

Guh, I tried working it all out with your formula for the remainder term and it didn't work. The reason? There's an error in your remainder formula, the real form is: R_{n}(x) = \frac{1}{n!}\int_{a}^{x}(x-t)^{n}f^{(n+1)}(t)dt It works with that formula, look at the wi...

- Fri Jan 07, 2011 11:10 pm UTC
- Forum: Science
- Topic: Aluminum foil in a microwave - when should you be worried?
- Replies:
**24** - Views:
**14142**

### Re: Aluminum foil in a microwave - when should you be worrie

Sparks in a microwave are never a good thing and people are in the right state of mind to run over and turn it off. WHY is it never a good thing? It seems like you are just repeating what someone else told you without having any practical knowledge of the subject at all. Are you kidding me? How can...

- Fri Jan 07, 2011 5:09 pm UTC
- Forum: Science
- Topic: Aluminum foil in a microwave - when should you be worried?
- Replies:
**24** - Views:
**14142**

### Re: Aluminum foil in a microwave - when should you be worrie

Sparks in a microwave are never a good thing and people are in the right state of mind to run over and turn it off. WHY is it never a good thing? It seems like you are just repeating what someone else told you without having any practical knowledge of the subject at all. Are you kidding me? How can...

- Thu Jan 06, 2011 11:09 pm UTC
- Forum: Science
- Topic: Aluminum foil in a microwave - when should you be worried?
- Replies:
**24** - Views:
**14142**

### Re: Aluminum foil in a microwave - when should you be worrie

Do you have an oven? Easy solution to heat it up = throw it in your oven. This avoids the issue with your microwave. Sparks in a microwave are never a good thing and people are in the right state of mind to run over and turn it off. However I could go on a huge shpleel about what's already said but ...

- Wed Jan 05, 2011 11:02 pm UTC
- Forum: Science
- Topic: scientific field
- Replies:
**22** - Views:
**3155**

### Re: scientific field

I'll warn you right now that what you have a 'passion' for in high school may not be where you end up throughout university and further. I was a die-hard Chemistry lover in high school. I loathed going to biology and physics but i did it anyway because of the credits required to get into university....

- Fri Dec 17, 2010 4:40 am UTC
- Forum: Science
- Topic: Privatized Space Travel
- Replies:
**148** - Views:
**11606**

### Re: Privatized Space Travel

To mars and back? That's going to be a little longer than a 'couple hours', try nearly a year to get there, same on the return trip.

- Wed Dec 08, 2010 4:56 am UTC
- Forum: Science
- Topic: Can someone explain the joke?
- Replies:
**16** - Views:
**3056**

### Re: Can someone explain the joke?

I think the joke is just that in Physics, everyone tries to make their equations more elegant and simple, by using modified notation and super/subscripts to represent longer equations. And from what I understand, there is an inherent understanding that 'the more elegant the solution, the more likely...

- Wed Nov 24, 2010 2:24 am UTC
- Forum: Mathematics
- Topic: [DONE, Thank you!] Laplace Transform contradiction??
- Replies:
**9** - Views:
**1198**

### Re: [HWK help] Laplace Transform contradiction??

I observe that it'd work out nicely if you had 32s^2 rather than just 32s in the first term you produced for the second method. Perhaps you might want to look closely at your work surrounding that term to see if you may have lost a factor of s? Yep... I screwed up taking the second derivative... Ou...

- Wed Nov 24, 2010 2:18 am UTC
- Forum: Mathematics
- Topic: [DONE, Thank you!] Laplace Transform contradiction??
- Replies:
**9** - Views:
**1198**

### Re: [HWK help] Laplace Transform contradiction??

How? Expanding out

[math]F(s) = \frac{32s}{(s^2 + 16)^3} - \frac{8}{(s^2 + 16)^2}[/math]

doesn't give me

[math]F(s) = \frac{24s^2 - 128}{(s^2 + 16)^3}[/math]

when I expand it out I get:

[math]\frac{-8s^2 + 32s - 128}{(s^2 + 16)^3}[/math]

[math]F(s) = \frac{32s}{(s^2 + 16)^3} - \frac{8}{(s^2 + 16)^2}[/math]

doesn't give me

[math]F(s) = \frac{24s^2 - 128}{(s^2 + 16)^3}[/math]

when I expand it out I get:

[math]\frac{-8s^2 + 32s - 128}{(s^2 + 16)^3}[/math]

- Wed Nov 24, 2010 2:10 am UTC
- Forum: Mathematics
- Topic: [DONE, Thank you!] Laplace Transform contradiction??
- Replies:
**9** - Views:
**1198**

### Re: [HWK help] Laplace Transform contradiction??

How so? Doesn't (-t)^2sin(4t) imply the 2nd derivative of the laplace transform of sin(4t)? That's what I have in my notes :S edit - well if you want to be 100% correct F^{(2)}(s) = Laplace of (-t)^2 f(t) Where f(t) = sin(4t), thus the second derivative of F(s) = lapl...

- Wed Nov 24, 2010 1:43 am UTC
- Forum: Mathematics
- Topic: [DONE, Thank you!] Laplace Transform contradiction??
- Replies:
**9** - Views:
**1198**

### Re: [HWK help] Laplace Transform contradiction??

=( 46 views and not a single suggestion? I put a lot of work into making the latex notation all nice.

- Wed Nov 24, 2010 1:39 am UTC
- Forum: Science
- Topic: Thanksgiving take-home physics quiz...
- Replies:
**15** - Views:
**1970**

### Re: Thanksgiving take-home physics quiz...

Not really what I meant: if we have t = k W^2/3, then by dimensional analysis we have [k] = [t]/[W^2/3], in SI we get [k] = \frac{s}{\frac{kg^{2/3}m^{2/3}}{s^{4/3}}} or [k] = \frac{s^{7/3}}{kg^{2/3}m^{2/3}} so k = 0.66 \frac{s^{7/3}}{kg^{2/3}m^{2/3}} But... you know, that only works for a 3 dimensio...

- Wed Nov 24, 2010 12:28 am UTC
- Forum: Science
- Topic: Thanksgiving take-home physics quiz...
- Replies:
**15** - Views:
**1970**

### Re: Thanksgiving take-home physics quiz...

Perhaps assume 0.66 is a constant with units that makes it compute?

- Tue Nov 23, 2010 7:21 pm UTC
- Forum: Mathematics
- Topic: [DONE, Thank you!] Laplace Transform contradiction??
- Replies:
**9** - Views:
**1198**

### [DONE, Thank you!] Laplace Transform contradiction??

As part of a homework assignment we were given the following problem: Find the laplace transform (how do I do the L symbol???) of t^2sin(4t) using first principles, then confirm your answer using the differentiation rule Using sin(4t) = \frac{e^{i4t}-e^{-i4t}}{2i} Plugging into the d...

- Mon Nov 15, 2010 8:58 pm UTC
- Forum: Fictional Science
- Topic: Clarke's Third Law and Harry Potter.
- Replies:
**21** - Views:
**6674**

### Re: Clarke's Third Law and Harry Potter.

You could get some sulfer-hexafluoride and either a) make your voice awesome, or b) make stuff levitate

- Fri Nov 12, 2010 3:58 am UTC
- Forum: Science
- Topic: [HOMEWORK] Electromagnetic induction problem (spinning loop)
- Replies:
**1** - Views:
**626**

### Re: [HOMEWORK] Electromagnetic induction problem (spinning l

Thinking about it some more, if I define the following: current loop.jpg and take the following integral: \int_0^L{\omega B r d\vec{l}} = \omega B r \int_0^L{d\vec{l}} = \omega B r L This will give me half the area, but I am only taking into account the upper half of the loop, thus I multiply my res...

- Fri Nov 12, 2010 3:30 am UTC
- Forum: Science
- Topic: [HOMEWORK] Electromagnetic induction problem (spinning loop)
- Replies:
**1** - Views:
**626**

### [HOMEWORK] Electromagnetic induction problem (spinning loop)

So i've been scratching my head with this problem for a while now and was hoping someone could either say yay my solution is correct or to point me in the right direction: Supposed the loop in [the picture below] is rotated around the y axis. What is the maximum emf when \omega = 35.0rad/s, B = 0.45...

- Sat Nov 06, 2010 5:12 pm UTC
- Forum: Science
- Topic: Guy on facebook page denies germ theory
- Replies:
**39** - Views:
**5976**

### Re: Guy on facebook page denies germ theory

Huh... you think an ethics board would have some issues with deliberately infecting people. Well then...

- Sat Nov 06, 2010 5:41 am UTC
- Forum: Science
- Topic: Guy on facebook page denies germ theory
- Replies:
**39** - Views:
**5976**

### Re: Guy on facebook page denies germ theory

If it weren't for ethics boards we could prove this easily. Identify a culture of said germs, keep a group of people in sterile isolation for several months, as to set them as a control. Split into 2 (or several) groups. Introduce 1 group to the 'germs', keep the other group neutral. Who develops th...

- Thu Nov 04, 2010 3:21 am UTC
- Forum: Science
- Topic: Chemistry Safety
- Replies:
**24** - Views:
**2422**

### Re: Chemistry Safety

gotta make sure they dont touch the liquid though of course. When I was a kid they had an open day at the university. LN is one of those weird substances which is both dangerous but also surprisingly hard to injure yourself with. They did all the tricks,poured some out on the ground and me and the ...

- Tue Nov 02, 2010 2:46 am UTC
- Forum: Science
- Topic: Chemistry Safety
- Replies:
**24** - Views:
**2422**

### Re: Chemistry Safety

Sodium Thiocyanate has a pretty vicious MSDS sheet: (This is for a 98-100% concentration of the stuff, check what % your mixture is, the less it is the less harmful it will be) http://www.jtbaker.com/msds/englishhtml/s5210.htm Inhalation: May cause irritation to the respiratory tract. Symptoms may i...

- Tue Nov 02, 2010 2:10 am UTC
- Forum: Science
- Topic: AP Physics problem-- pulleys (of the frictionless variety)
- Replies:
**16** - Views:
**3523**

### Re: AP Physics problem-- pulleys (of the frictionless variet

Ok then, instead of being rude maybe we should actually help this guy. Look at each pully and draw the free body diagram for it, look at the mass hanging, what are the forces acting on it? How do they balance? To get you started I drew the FBD's for you: I hope the picture makes sense, I haven't rea...