Question

Which describes the role the particles of objects play in attaining thermal equilibrium?

A.
Colliding particles absorb thermal energy from the air until particles in both the warm and cold object reach the same temperature.

B.
Colliding particles exchange kinetic energy until particles in both the warm and cold object move at the same rate.

C.
Colliding particles exchange potential energy until particles in both the warm and cold object reach the same temperature.

Answer 1

Colliding particles absorb heat energy from the air until particles in both the warm and cold object reach the same level of thermal energy.

Answer 2

I think it's D

Answer 3

I think so too.

Answer 4

Is heat energy really a thing? Heat is more a process, it was only thought to be an actual thing. Now I think we refer to it as thermal energy, if anything.

Temperature is related to but is not kinetic energy. Potential energy is the same thing.

Answer 5

The answer to this question is B. Temperature in many cases is essentially equivalent to kinetic energy, and I'm not sure where you're getting the idea that potential energy is somehow the same.

Answer 6

I was saying that potential energy is the same as kinetic energy in the respect that it is not temperature, but can rather be related to it. Kinetic energy is not temperature, as you pointed out.

Answer 7

I am still not sure how you would relate potential energy to temperature.

Answer 8

Me neither! I also don't know how to relate the kinetic energy to the temperature. But I know kinetic energy and temperature are closely related. I know that there is chemical potential energy, and the energy due to pressure, and I think we can consider them as potential energies of a macroscopic system.

Like, if you have a piston pressurize its chamber, some of the energy used to cause that change in pressure is now considered stored potential energy. That chamber has the ability to due work.

Just as a side note, since this is thermodynamics, some of the work done on the piston becomes unusable energy, at least some of which contributes to a rise in the temperature.

I know you can use the thermodynamic potentials (not potential energies, I know) to describe the temperature using other quantities. They are sufficient to describe the macroscopic state of a system. Wikipedia knows more than I do, so if you want to look at that, here's the link!
http://en.wikipedia.org/wiki/Thermodynamic_potential

I don't know a whole lot, but I'll help if I can. I'm pretty weak in thermodynamics. I just contributed because I really didn't think D was an acceptable answer.
The word "heat" isn't used as a property like it used to be. We say "heating" and "heat transfer," but we're really talking about temperature change. That's different than when they used "heat" as a scientific property, because they decided that there is now thing that flows from one thing to another.
So heat energy sounded silly, and I never heard of thermal energy. I can't understand the idea of exchanging potential energy, and I thought that the kinetic energy of particles thing wasn't accurate based on something from high school, I think.

Kinetic energy seems weird if it's still \(\frac12mv^2\). If I put a cold brick in warm air in an "incompressible, isolated, and impermeable" room, they will reach thermal equilibrium. But I don't think the brick molecules and air molecules would be moving at the same rate.

@jemurray3 , feel free to let me know if I've gone wrong anywhere! Or if you want to point something else out. Or we can discontinue this post, as you've answered the question, it has been closed, and it might be the case that other people involved aren't interested. But maybe random internet people will be, I don't know!

Answer 9

In an ideal gas at equilibrium, the average energy per particle is \( \frac{3}{2} k_B T \), where \(k_B\) is the Boltzmann constant. In that sense, the (kinetic) energy is almost exactly equal to the temperature (conceptually, not numerically). For solids, there is a similar relationship, whereby the average energy per particle is \(3k_BT\). Half of this is kinetic energy, while the other half is the potential energy of the "springs" (bonds) holding the atoms and molecules together. The general form of this relationship is called the Equipartition theorem.

But this is "internal" energy - energy intrinsic to the system. If you consider the potential energy that you get from raising a block of metal up onto a shelf, then this is *external* potential energy and therefore cannot be related to the temperature in that way.

Answer 10

Most of that made sense, thanks :)
I remember learning \(E=\frac32k_BT\). So this energy is mostly the average kinetic energy of the system?

Answer 11

For an ideal gas, there is no other energy possessed by the particles.

Answer 12

Ohhhh, that makes sense.. Thanks :)

Answer 13

Thanks for the help!