# Homework Help: Need help quick with frictional force

1. Oct 20, 2008

### jayyafeelme

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

A force of 43.0 N accelerates a 5.0-kg block at 6.1 m/s2 along a horizontal surface.
How large is the frictional force?

What is the coefficient of friction?

2. Relevant equations
F = ukFn

3. The attempt at a solution
Fthrust = Ffriction = ukFn = ukFg = uk x m x g = ? x 5.0 kg x 6.1 m/s/s

Last edited: Oct 20, 2008
2. Oct 20, 2008

### jayyafeelme

no one can help me?

3. Oct 20, 2008

### jayyafeelme

4. Oct 20, 2008

### borgwal

What's the total force on the block?

5. Oct 20, 2008

### jayyafeelme

43 N i think. thats all the givens i have

6. Oct 21, 2008

### borgwal

No, you clearly have more "givens." And 43 N is NOT the total force.

7. Oct 21, 2008

### Garicup

here the net force of the system is ma

take the forces, -------->u have the applied force...(43N) and the force against it which u dont have (Ff) and equate it to the net force

so, ma = Fapplied - Ffriction

i thinks thats how u solve it...i can be wrong...

once you solve for friction force, you can easily solve for mu by with Ff = muFn

8. Oct 21, 2008

### borgwal

Yes, that's how you solve it, but it gives a bit too much information. The poster has to do some work too!