# Homework Help: Elastic Potential Energy- finding spring constant

1. Jun 6, 2009

### bigboss

1. The problem statement, all variables and given/known data

In a physics lab experiment, a spring clamped to the table shoots a 22 g ball horizontally. When the spring is compressed 18 cm, the ball travels horizontally 5.2 m and lands on the floor 1.5 m below the point at which it left the spring.

2. Relevant equations

Us= .5kx^2

3. The attempt at a solution

I tried to find the elastic potential energy and then i got stuck.

2. Jun 6, 2009

### Cyosis

Use energy conservation. When the spring is compressed the ball is stationary so all its energy is elastic potential energy. When the spring is released the ball loses potential energy and gains kinetic energy.

3. Jun 7, 2009

### bigboss

how would i find the velocity?

4. Jun 7, 2009

### Cyosis

With $y=y_0+v_{0,y}t-\frac{1}{2}gt^2$ and $x=v_{0,x} t$.