# Homework Help: Box collides with a spring

1. Nov 2, 2007

### 1stimer

1. The problem statement, all variables and given/known data
1.5kg box sliding on frictionless surface with a speed of 12m/s approaches a horizontal spring. The spring has a k of 2000N/m. How far will the spring be compressed in stopping the box? How far will the spring be compresses when the box's speed is reduced to half its initial speed?

2. Relevant equations
Fs=-kx
W=1/2kx^2

3. The attempt at a solution

Not sure if I needed this but I found the KE to be 108J. I tried to solve for x by 1.5kgx9.80m/s^2/2000N/m= .007m. Not sure!

2. Nov 2, 2007

### Astronuc

Staff Emeritus
Try this - http://hyperphysics.phy-astr.gsu.edu/hbase/pespr.html

One is correct about the kinetic energy. Without dissipative forces, e.g. friction, the kinetic energy of the traveling mass will be transformed into the stored mechanical energy of the spring.

The acceleration of gravity is not part of this.

3. Nov 2, 2007

### 1stimer

I put in the 2000N/m and 108J and got 0.3m?