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?

Answer 1

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.