The Second Law
No engine that takes heat Q1 at T1 and delivers heat Q2 at T2 can do more work than a reversible engine
- W = Q1 – Q2 = Q1(T1 – T2) / T1
Assume that the whole world was at the same temperature
- We could convert work into heat
- Example: We can make heat by friction
- We could not convert heat into work
- Example: We cannot reverse friction and make heat do work
Heat will not, by itself, flow from a cold object to a hot object