# Friction Force

1. Dec 10, 2004

### lostinthespiral

I am having real problems understanding friction and how it relates to problems. Right now all I have to work with is a Cal-oriented book, but the class I'm in is taught with just Trig. I am completely lost. Your help would be greatly appreciated.

Starting from rest, a 4.33 kg block slides 2.82 m down a rough 25.8 degree incline. The coeficient of kinetic friction between the block and the incline is 0.481. The acceleration of gravity is 9.8 m/s2.

a.) Find the work done by the force of gravity. Answer in units of J.
b.) Find the work done by the friction force between block and incline. Answer in units of J.
c.) Find the work done by the normal force. Answer in units of J.

2. Dec 10, 2004

### Pyrrhus

Well, what have you done??

Did you draw the free body diagram?

3. Dec 10, 2004

### futb0l

Yupp - cyclovenom said it - Draw a free diagram - label all the forces, including the normal force and the force parallel to the surface.

Remember from the last problem I helped u with that

$$F_{friction} = \mu N$$