Question

what does the 2nd law of thermodynamics state about the amount of useful energy out of a system compared to the total amount of energy put into that system?
useful energy out is not correlated to total energy in.
useful energy out is always less than total energy in.
useful energy out is always more than total energy in.
useful energy out is always double the total energy in.

Explanation:

The 2nd law of thermodynamics accounts for energy losses (like heat) in any system, meaning not all input energy can be converted to useful work.

Answer:

Useful energy out is always LESS than total energy in.