What happens to energy in a spring when it oscillates?

[tcharger130]

Homework Statement

For my lab we measured potential energy with a mass on a spring. One of the questions is: When the spring is allowed to oscillate for some time, its amplitude becomes smaller until it eventually comes to a rest. What happens to the energy stored in the spring (What form of energy is it converted to)?

Homework Equations

None

The Attempt at a Solution

I assume it is talking about the restoring force becoming greater than the force of gravity on the mass, but I don't know what form of energy it changes into.

Thanks.

 

[rock.freak667]

In ideal cases, for conservation of mechanical energy PE+KE= constant.

But in practical cases, what cannot be left out? (What makes a car slow down when the brake pedal is pressed down?)