# Box with mass attached to spring and board

1. Oct 13, 2008

### 12boone

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

A 0.580Kg wood block is firmly attached to a very light horizontal spring. It is noted that the block-spring system (k=160N/m), when compressed 4.0cm and released, stretches out 0.9 cm beyond the equilibrium position before stopping and turning back.

2. Relevant equations

Conservation of Mechanical Energy

KEf+PEf=KEi+PEi

and

1/2kx^2

3. The attempt at a solution

Ok, What I tried to do is solve for the work of friction using

(coefficient of friction)(Normal Force)(d)=1/2k(xf-xi)^2. However, I do not understand what the problem is asking as far as distances. I converted the distance to m but I still do not know what they mean by compressed for 4 cm. Does that mean they pushed it 4 cm forward. Let it go and it went past its resting point .9 cm. If so is .9 negative? or is 4 cm negative?

2. Oct 13, 2008

### Hootenanny

Staff Emeritus
That would be correct.

However, you have failed to state what the question is asking you to find.

3. Oct 13, 2008

### 12boone

what im looking for is the coefficient of friction.

4. Oct 13, 2008

### Hootenanny

Staff Emeritus
Ahh right. Looking back at the question, is doesn't matter which (extension/compression) you choose as positive and which you choose as negative provided that one is positive and one is negative.

Your approach is correct by the way.