How Many Laws of Thermodynamics Are There?

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The discussion centers on the number of laws of thermodynamics, with participants noting that there are four recognized laws, including the 0th law, which addresses thermal equilibrium. The 1st law emphasizes the conservation of energy, stating that heat equals the change in internal energy plus work done on the system. The 2nd law highlights that entropy tends to increase over time, while the 3rd law states that absolute zero cannot be reached. Participants express confusion about the laws and seek clarification on the implications of absolute zero in relation to quantum mechanics. The conversation reflects a mix of formal definitions and informal interpretations of the laws.
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How many laws of thermodinamics are there?

This topic came up during one of our last hours of higschool physics. Some of us sead that there are 4 and some sead that there are only 2. In different books we also found different answeres. So now I really don't know which statement is corect. Any ideas?
 
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0th law - If a system, C is in thermal equilibrium with two other systems, A and B, then A and B must also be in thermal equilibrium.

1st law - Heat = Change in Internal Energy + Work done on the system. (Conservation of energy effectively).

2nd law - Entropy always increases with time.

3rd law - No object can ever reach a temperature of absolute zero.

A nice discussion of laws 1-3 can be found here.
http://www.physlink.com/Education/AskExperts/ae280.cfm

Claude.
 
1st Law: You can't win; you can only break even

2nd Law: You can only break even if you get to absolute zero.

3rd Law: You can't get to absolute zero.
 
rdt2 said:
1st Law: You can't win; you can only break even

2nd Law: You can only break even if you get to absolute zero.

3rd Law: You can't get to absolute zero.

you are forgetting a law here, see the above post

marlon
 
But i don't know why we can not reach the zero absolute temperature. Who can explain?
 
Essentially, because a particle at 0K violates the HUP. Google the 3rd law of thermodynamics and you should find some satisfying explanations.

Claude.
 

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