# Coefficient of friction formulas help

1. Nov 3, 2004

### Kdawg

A 52-N sled is pulled across a cement sidewalk at a constant speed. A horizontal force of 36 N is exerted. What is the coefficient of sliding friction between the sidewalk and the metal runners of the sled?
What formulas would I use in this problem?

2. Nov 4, 2004

### nelufar

It is simple !
Use the formula,
[TEX] F = {\mu}_s * N [/TEX]
where F is the horizontal force and N is the normal force, which is equal to the weight of the sled. (I assume that the cement sidewalk is placed horizontally).

Last edited: Nov 4, 2004
3. Nov 6, 2004

### gauravkukreja

Notice that the body is moving with uniform accelaration.
This means that the net force acting on the body is 0.
Therefore, $$\mu * 52 N = 36 N$$
This gives, $$\mu = 36 / 52$$

4. Nov 6, 2004

### brewnog

The body is moving with uniform *velocity*, not acceleration, otherwise the net force on the body would not be zero.