Can Heat Flow from Cold to Hot?

In summary, the conversation discusses the possibility of heat flow from a slower heavy atom to a faster moving atom. The participants clarify that it is energy transfer, not momentum transfer, that is relevant in this scenario. They also mention the potential for a faster molecule to gain energy from a slower molecule in an oblique collision, but this would not be considered a flow of heat unless there is a net transfer of energy for many molecules.
  • #1
NicholasB54
2
0
If heat flow is the momentum change from a faster moving atom or molecule to a slower moving one, and momentum is mass x velocity is it possible - for a very limited amount - for heat to flow from a slower (colder) heavy atom to a faster moving (hotter) atom ?
 
Science news on Phys.org
  • #2
(1) It's energy transfer, not momentum transfer, that's relevant.

(2) It is, I believe, possible in an oblique collision for a faster molecule to pick up speed (and hence KE) from a slower molecule of the same mass.

(3) But we wouldn't classify this as a flow of heat. To constitute a flow of heat we'd need a net transfer of energy for many molecules.
 
  • #3
I was confusing energy change and momentum change alright

Thanks Philip
 

1. Can heat flow from cold to hot?

Yes, under certain conditions heat can flow from cold to hot. This phenomenon is known as the "heat creep" or "heat transfer paradox". It occurs when there is a temperature difference between two bodies, and the colder body is able to absorb heat from the hotter body due to thermal radiation or conduction.

2. How is heat able to flow from cold to hot?

Heat flow from cold to hot is possible due to the second law of thermodynamics, which states that heat will flow spontaneously from a hot object to a cold object. However, this law does not specify the direction of heat flow, meaning that heat can also flow from cold to hot under certain conditions.

3. What are the conditions required for heat to flow from cold to hot?

There are three main conditions required for heat to flow from cold to hot. First, there must be a temperature difference between the two bodies. Second, there must be a medium through which the heat can be transferred, such as air or a solid material. Finally, the colder body must be able to absorb heat through thermal radiation or conduction.

4. Is heat flow from cold to hot a common occurrence?

No, heat flow from cold to hot is not a common occurrence in everyday life. It is more commonly observed in certain industrial processes, such as refrigeration and air conditioning systems, where heat is purposely transferred from a colder medium to a hotter one.

5. Are there any practical applications for heat flow from cold to hot?

Yes, there are some practical applications for heat flow from cold to hot. As mentioned before, it is used in refrigeration and air conditioning systems. It is also utilized in thermoelectric devices, such as thermocouples, which convert temperature differences into electrical energy.

Similar threads

Replies
21
Views
1K
  • Thermodynamics
Replies
4
Views
1K
Replies
6
Views
3K
Replies
14
Views
1K
  • Thermodynamics
Replies
7
Views
922
Replies
32
Views
2K
  • Materials and Chemical Engineering
Replies
6
Views
414
  • Thermodynamics
Replies
20
Views
9K
  • Thermodynamics
Replies
33
Views
1K
  • Thermodynamics
Replies
26
Views
1K
Back
Top