Ask a Physicist Anything!

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Colytic
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Re: Ask a Physicist Anything!

Postby Colytic » Sun Oct 25, 2015 2:33 pm

[mod edit: corrected boltzmann's name]


Good old kudayta!
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UNITEDAIR
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Re: Ask a Physicist Anything!

Postby UNITEDAIR » Tue Oct 27, 2015 7:55 pm

I am a bit disturbed by the fact that a mod/admin can directly edit my post.

Edit: R u not aware???? - Vic :mrgreen:

Edit: Just in time for Halloween. It's the Spooky Mod Edition! - kud

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Re: Ask a Physicist Anything!

Postby DTNC Vicious » Wed Oct 28, 2015 7:43 pm

Spooooooooooooky
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UNITEDAIR
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Re: Ask a Physicist Anything!

Postby UNITEDAIR » Wed Oct 28, 2015 10:40 pm

Scary Skeleton .....
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Mr.Megadeath
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Re: Ask a Physicist Anything!

Postby Mr.Megadeath » Thu Oct 29, 2015 1:34 am

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nuclear cocaine
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Re: Ask a Physicist Anything!

Postby nuclear cocaine » Fri Nov 06, 2015 8:38 am

Here's a simple one ..... If hot water freezes to ice faster than cold water. Does cold water get hot faster than room temperature water?
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UNITEDAIR
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Re: Ask a Physicist Anything!

Postby UNITEDAIR » Fri Nov 06, 2015 5:41 pm

Excellent question and far from simple.
The effect you describe is called the Mpemba effect, and the exact reason why it happen under certain circumstances is sort of unclear. Various explanation have been proposed that ranges from supercooling effect to dissolved gasses in the water to the thermal conductivity of how the water freezer since ice acts as an insulator, does it mean when frost is first observed or the entire volume is solid? Perhaps convection.
Here is a paper : http://arxiv.org/abs/physics/0512262v1

It seems logical to then suggest that then cold water would then get hotter than warmer water.
Sort of. It doesn't reach boiling point faster than room temperature or hot water if that is what you're asking.
It is true that cold water, under a heat source, will initially get warmer faster, than a warmer water under the same heat source.
This is because the heat gradient is larger for the cold water than hot water. However, as the temperature of the water increases, the heat difference decreases and the rate of temperature increases slows.
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Mr.Megadeath
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Re: Ask a Physicist Anything!

Postby Mr.Megadeath » Fri Nov 06, 2015 9:05 pm

Is the ocean salty because land doesn't wave back?
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Re: Ask a Physicist Anything!

Postby UNITEDAIR » Fri Nov 06, 2015 10:30 pm

Of course the land waves back.
Here is a video of what happens when that occurs:
https://www.youtube.com/watch?v=3xKMFzKOIfQ
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Re: Ask a Physicist Anything!

Postby Mr.Megadeath » Sat Nov 07, 2015 1:47 am

Ok here is another question for you then. If Jesus died for our sins then who died for our Cos and Tans?
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kudayta
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Re: Ask a Physicist Anything!

Postby kudayta » Sat Nov 07, 2015 4:44 am

Hermaeus Mora wrote:Ok here is another question for you then. If Jesus died for our sins then who died for our Cos and Tans?


Jose and Sergio respectively.
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Re: Ask a Physicist Anything!

Postby cza » Wed Nov 11, 2015 7:33 am

Schubdüse wrote:Ask a Physicist Anything...
But let's try: How do I move my index finger?
(Cut the crap and don't lecture me about actin, myosin, motoneurons, acetylcholine etc. Explain me the trigger? What is the "photon", the "soundwave", the ligand to the smell or taste receptor, the pressure or heat sensor which makes my finger move, if I WANT to?)



I always told you guys Schub-a-dub was a lover.
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Re: Ask a Physicist Anything!

Postby UNITEDAIR » Thu Nov 12, 2015 8:14 pm

cza wrote:
I always told you guys Schub-a-dub was a lover.


scub-a-dub-a-dub-a-doo
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Re: Ask a Physicist Anything!

Postby FreeZer » Sun Nov 22, 2015 8:25 pm

Mike Tevee should be able to try an answer on that Schub! I think Roger Penrose work is quite on the track. :D
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Re: Ask a Physicist Anything!

Postby UNITEDAIR » Mon Nov 23, 2015 3:27 am

I don't understand.

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