Chapter 6, Problem 17RQ

Is a machine that has efficiency greater than $100\%$ physically possible? Discuss.

To determine

Whether the efficiency of a machine cannot be $100\%$.

Answer to Problem 17RQ

The efficiency of a machine cannot be $100\%$.

Explanation of Solution

The efficiency a machine cannot be $100\%$, it is always less than $100\%$. By the laws of thermodynamics, input work totally cannot be converted into total output, some of the energy is rejected in the form of heat.

Because of friction, air resistance and many other factors affect the efficiency of the machine. In order to actually exceed $100\%$, the machine would have to create energy from nothing and in this universe, that isn't happening. This is against the nature as well as the law of thermodynamics,

Conclusion:

Therefore, the efficiency of a machine cannot be $100\%$.