Calculating Coefficient of Friction on Inclined Surface

[Inertialforce]

Homework Statement

A block is placed onto a ramp. The ramp's angle of inclination is adjustable. Show that when the ramp is raised to the point where the block is just about to begin slipping the coefficient of friction can be determined from: μ= tan(theta) where (theta) is the angle of inclination when the block begins to slip.

Homework Equations

ΣFx and ΣFy

The Attempt at a Solution

I am not quite sure how to start this because even though we did learn contact forces in class, all the examples and questions that we have had so far were objects in contact with each other along a flat horizontal surface where angles were not needed.

 

[phyguy321]

Draw a picture!
Include all your forces, i.e. where they are and what direction they are going.
Find your normal force with respect to the ramp and take into account the angle using basic trig.
In the end things should start to cancel out.