You place a book on top of a spring and push down, compressing the spring by 10 cm. When you let go of the book, it is pushed up by the spring. Which statement describes what happens to the energy of the spring-book system?

A. The total energy of the system remains constant.
B. The elastic potential energy of the system increases.
C. The kinetic energy of the system decreases.
D. The gravitational potential energy of the system decreases.

Question

You place a book on top of a spring and push down, compressing the spring by 10 cm. When you let go of the book, it is pushed up by the spring. Which statement describes what happens to the energy of the spring-book system?

 		A.	The total energy of the system remains constant.
 		B.	The elastic potential energy of the system increases.
 		C.	The kinetic energy of the system decreases.
 		D.	The gravitational potential energy of the system decreases.

wolfe8 · Answer

When you press the spring, you are supplying adding its potential energy. When it bounces back it releases that energy in the form of kinetic energy. So what do you think?