What are the 1st and 2nd laws of thermodynamics?

1 Answer
Mar 24, 2018


Please see below.


First law of thermodynamics is an extension of the law of conservation of energy. It says that the change in internal energy of a system is constant i.e. change is equal to the heat added to the system minus the work done by the system.

Kelvin’s statement of Second law of thermodynamics says it is impossible to build a cyclic machine that converts heat into work with #100%# efficiency i.e. a machine will always loose some energy and one cannot convert #100%# of one form of energy into another form. The Clausius statement says that heat does not flow from a colder body to a hotter body, without a change outside of the two bodies.

The second law also introduces entropy, a measure of messiness or system disorder. A reversible process is one which can change state and then return to the original state. What second laws says is that processes are not reversible and entropy of a closed system will increase during any process and as such the entropy of the universe is continuously increasing.