Spring problem on work and force

[brnnpink4]

Homework Statement

a .4 kg mass compresses a spring of .2m. The spring constant is 400n/m How fast is the mass moving after the mass is released and the spring uncompresses? If the mass is going up a .5m hill, how fast is it going?

Homework Equations

PE+KE=w

PE=mgh

KE=.5mv^2

The Attempt at a Solution

PE=.5(9.8)(x)

 

[jackarms]

To find how fast its moving right after the spring decompresses, use energy conservation. Elastic potential energy is lost, and kinetic energy is gained.

You'll have to clarify the second part -- is the hill 0.5m high? Do you mean how fast is it going at the top?

 

[brnnpink4]

The hill is .5m high