The coefficient of static friction between the m = 3.20 kg crate and the 35.0° incline of the figure below is 0.340. What minimum force must be applied to the crate perpendicular to the incline to prevent the crate from sliding down the incline?

Question

The coefficient of static friction between the m = 3.20 kg crate and the 35.0° incline of the figure below is 0.340. What minimum force  must be applied to the crate perpendicular to the incline to prevent the crate from sliding down the incline?

bobpursley · Answer

I assume a crate is on an incline.

In this case, fricion + force applied has to be greater than the component of weight down the plane.

friction: mg*mu*CosTheta
weight down plane: mgSinTheta

force+friction=weight down plane
solve for force.