# Coefficient of friction

1. Dec 3, 2005

how do i find the coefficient of friction of a block?
is it Ff/Fn?
the problem is how do i find the friction force?

2. Dec 3, 2005

### Cyrus

What does the problem ask, the coefficient of friction of a block does not make sense. Its always between two surfaces.

3. Dec 3, 2005

### amcavoy

If I'm interpreting your question correctly, then you want to know whether the coefficient of friction is the frictional force divided by the normal force, right? This has been true for my uses of it, but there's probably a better definition somewhere.

4. Dec 3, 2005

### kaitamasaki

u = coefficient of friction
Ff = umg
u = Ff / mg
you need either one..
mg is also known as Fn

5. Dec 3, 2005

### Cyrus

Be careful kaitamasaki, Fr isint equal to umg.

6. Dec 3, 2005

### Staff: Mentor

Not clear whether you are trying to find the friction force or the coefficient of friction. (You've got to be given--or measure--something.) Also: Is the friction kinetic or static? Is the surface horizontal?