Coefficient of static friction of crate

[collegegirl]

Homework Statement

A 200N crate rests on a ramp, the angle is 20 degrees with the horizontal. What is the coefficient of static friction between the crate and ramp surfaces

Homework Equations

T=N/cos theta

The Attempt at a Solution

200/cos25 = 219

I don't know where to go from here. The answer is .47 Please show me a direction to take.!

 

[asleight]

Homework Statement

A 200N crate rests on a ramp, the angle is 20 degrees with the horizontal. What is the coefficient of static friction between the crate and ramp surfaces

Homework Equations

T=N/cos theta

The Attempt at a Solution

200/cos25 = 219

I don't know where to go from here. The answer is .47 Please show me a direction to take.!

What forces are acting upon the object? (Hint: There are three forces and one of these forces has components if you choose an efficient coordinate system.)

 

[collegegirl]

Would the three forces be gravity, the weight of the crate on the ramp, and the ramp pushing up on the crate? If so, the only one I have numbers for is gravity??

 

[asleight]

Would the three forces be gravity, the weight of the crate on the ramp, and the ramp pushing up on the crate? If so, the only one I have numbers for is gravity??

Weight and gravity are related by \vec{w}=m\vec{g}. The other two forces are going to be the frictional force (a function of the normal force) and the normal force, itself, a function of weight. So, where are your x- and y-axes going to lie?