- #1
zezima1
- 123
- 0
Is defined as F = U - TS and it is the energy needed to create a system minus the heat it can get for free.
But why is the heat that it can get for free given by:
Q = TS
I know the thermodynamic relation:
S = Q/T
So in that way I understand it. But how do you know, that the system will be in thermal equilibrium with surroundings, when it has received a total energy of Q = TS as heat? I mean, the point where heat stops interesting is when temperaturs are equal, i.e. when dS/dU is the same for both systems. How do you know that holds when a total of heat of Q=TS has entered?
But why is the heat that it can get for free given by:
Q = TS
I know the thermodynamic relation:
S = Q/T
So in that way I understand it. But how do you know, that the system will be in thermal equilibrium with surroundings, when it has received a total energy of Q = TS as heat? I mean, the point where heat stops interesting is when temperaturs are equal, i.e. when dS/dU is the same for both systems. How do you know that holds when a total of heat of Q=TS has entered?