# Homework Help: Work Problem Help!

1. Oct 12, 2012

### NasuSama

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

A 31.3 kg sled starts at rest on a horizontal road. The coefficient of kinetic friction between the sled and the road is μk = 0.23. A man pulls the sled a distance 8.75 m along the ground by exerting a constant force of magnitude 257 N on a rope that makes a 23.7o angle above the horizontal. Find:

2. Relevant equations

Hm..

W_f = mgdµ_k?

3. The attempt at a solution

Got 618 as the answer, but it's wrong.

2. Oct 12, 2012

### SHISHKABOB

first find the net force acting on the sled in the x direction

3. Oct 12, 2012

### NasuSama

OK. What I have is...

F_net = F_app - F_frictional
= 257cos(23.7) - 31.3 * 9.81 * 0.23
≈ 165

Then, what? Multiply that by the distance to get the work done?

4. Oct 12, 2012

### NasuSama

Actually, I found the normal force which is 204. Then, I need to use that to determine the work done! My bad.. -___-

5. Oct 12, 2012

### SHISHKABOB

so... problem solved?

6. Oct 12, 2012

### nasu

Find what??

7. Oct 12, 2012

### NasuSama

I guess so. Here is what I have...

W = (2060 - 204 * .23)8.75 = 1650

Am I on the right track?

Last edited: Oct 12, 2012