A horizontal spring on a frictionless surface with a spring constant of 40 N/m is compressed 0.3 m away from equilibrium and it is held at rest. A 2 kg mass is attached at the end of the spring. The spring-mass system is released from rest. Calculate the initial elastic potential energy stored in the spring before it was released.

A horizontal spring on a frictionless surface with a spring constant of 40 N/m is compressed 0.3 m away from equilibrium and it is held at rest. A 2 kg mass is attached at the end of the spring. The spring-mass system is released from rest. Calculate the initial elastic potential energy stored in the spring before it was released.