Finding Maximum Weight on a Ramp with Coefficients of Friction

[kari82]

I have the solution of this problem, but I would like someone to give me some guidance on how to begin solving the problem. Thanks!

A 1520-N crate is to be held in place on a ramp that rises at 30.0° above the horizontal (see Fig. CH 5-6.15). The massless rope attached to the crate makes a 22.0° angle above the surface of the ramp. The coefficients of friction between the crate and the surface of the ramp are µk = 0.450 and µs = 0.650. The pulley has no appreciable mass or friction. What is the maximum weight w needed to hold this crate stationary on the ramp?

solution= 1380N

 

[bjd40@hotmail.com]

draw a free body diagram of the crate. vector sum of horizontal forces as well as vertical forces will be zero. from this u can find w.