# Static friction on a slope.

1. Jun 18, 2012

A block is sliding down a 30° incline at 1.2ms^-2
Find the coefficient of static friction.
[g=9.8ms^2]

I am stumped..

Some relevant equations:
Fr = μ(Fn)
Fn = mg

Ultimately I got μ=0.5 ---> This was through mashing and playing with some trig.

Last edited: Jun 18, 2012
2. Jun 18, 2012

### Staff: Mentor

If the block is already sliding down the incline, then you don't have the information you need to determine the coefficient of static friction. On the other hand, you do have the information you need to determine the coefficient of kinetic friction. What are the components of the gravitational force on the block in the directions tangent and normal to the incline? Is the block accelerating in the direction normal to the incline? Is the block accelerating in the direction tangent to the incline? What are the force components acting on the block in the direction tangent to the incline? What is the normal force exerted by the incline on the block?