The coefficient of static friction between the m = 3.75-kg crate and the 35.0° incline of the figure below is 0.320. What minimum force vector F must be applied to the crate perpendicular to the incline to prevent the crate from sliding down the incline?

Answer 1

gravity force down the plane=mg*cosTheta
friction force=mu(mg*sinTheta+F)

set them equal, solve for F