# Conservation of energy involving spring and friction

1. Oct 25, 2008

### IniquiTrance

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

A 0.62 kg wood block is firmly attached to a very light horizontal spring (k = 180 N/m) . This block-spring system, when compressed .05 m and released, stretches out 0.023 m beyond the equilibrium position before stopping and turning back.

What is the coefficient of kinetic friction between the block and the table?

3. The attempt at a solution

This is how far I've gotten:

At x = -.05, there is 0 kinetic energy, and potential energy = 1/2 kx2.

So:

1/2 kx2 = 1/2 mv22 + $$\mu$$mg(energy lost due to friction)

But this has 2 unknown variables.

Any help is greatly appreciated.

2. Oct 25, 2008

### IniquiTrance

Nevermind, figured it out.

1/2 kxinitial2 = 1/2 kx2final + $$\mu$$mg(abs((xfinal - xinitial))