human
Question: A perpetual motion machine is a theoretical device which, once started, continues to operate without any additional input of energy. Which statement describes why a perpetual motion machine is impossible to design?

Choices:
A) Energy can be converted into mass.
B) Friction reduces the efficiency in a system.
C) The amount of energy in a system remains constant.
D) Potential energy can be converted into kinetic energy.
gpt
The correct answer is 1: Friction reduces the efficiency in a system..