THERMO A car engine takes atmosphere air in at 20 degree C n

THERMO

A car engine takes atmosphere air in at 20 degree C, no fuel, and exhausts the air at -20 degree C, producing the work in the process. What do the first and second laws say about this?

Solution

The car engine whose sole purpose is taking atmospheric air at higher temperature ie; 20 degree celcius and rejecting air as exhaust at -20 degree celsius by producing work can be considered as a PERPETUAL MOTION MACHINE OF FIRST KIND or PMM1 which is impossible and whose efficiency is one. The loses in PMM1 is zero. ie; there are no heat loses, frictional loses or any kind of other loses in the whole process. Impossibility of PMM1 is called as 1st law of thermodynamics.

According to the second law of thermodynamics, heat will not flow from a higher temperature object to lower temperature object without an aid of external work acting on the system.This law is the basic of a heat engine. In this case Car\'s engine work as a heat engine.