Chapter 15, Problem 17Q

To determine

How the whimsically stated “you can’t get something for nothing” and “you can’t even break even” equivalent to the formal statements of first and second law of thermodynamic respectively.

Answer to Problem 17Q

Solution:

“You can’t get something for nothing” directs the concept of conservation of energy and “you can’t even break even” directs the fact that no machine is 100% efficient.

Explanation of Solution

Whimsically stated “you can’t get something for nothing” is equivalent to the formal statement that energy is conserved, energy can neither be created nor be destroyed. According to first law of thermodynamics$\Delta U=Q-W$, the internal energy of the system can only be changed when some external energy from the surrounding is given to the system or some work is done by the system on its surrounding, without change in Q and W the internal energy of an isolated system will remain constant.

Whimsically stated “you can’t even break even” is equivalent to the formal statement of second law of thermodynamic that no engine is 100% efficient. Even in the case of ideal heat engine if some input energy is given to produce output work then some heat is exhaust as waste. No input energy is completely transformed to output work without heat waste.