# Conceptual Friction Question

1. Sep 25, 2011

### mdawg467

1. The problem statement, all variables and given/known data
A 3-lb horizontal force is applied to a 10-lb block on a rough horizontal surface. The block is initially at rest. If $\mu$s is 0.5 and the $\mu$k is 0.4, the frictional force on the block is?

2. Relevant equations
FN=mg
Fk=$\mu$kFN
Fs,max=$\mu$sFN

3. The attempt at a solution
I found $\mu$s,max required to move the 10-lb block was 49.0 lb/ms^2..or approximately 22N.

Since the force being applied is 3-lb, or approximately 1.4N, then the frictional force must be equal to the force being applied correct?

Thanks.

2. Sep 26, 2011

### PeterO

Sounds good - especially in America where apparently the pound is a unit of Force, not a unit of mass.

3. Sep 26, 2011

### mdawg467

Thank you!
Yeah only here in America haha..