Comparison:
1)The first law of thermodynamics calculates the Carnot efficiency;
2)the second law of thermodynamics predicts: η= 1-T1/T2.
Method:
1)The first law: P=P (V, T), E=E (V, T) DE=Q-W==>η,Efficiency needs to be calculated and determined.
2)Second Law: Anti perpetual motion machine, guessing==>1-T1/T2.
Effect:
1)The first law: E, P, W, Q ,η of the cyclic process can be obtained,
2)Second Law: Only efficiency can be obtained:η= 1-T1/T2.