Question

A trolley of mass 0. 80 kg runs freely, without accelerating, down an inclined plane when the plane makes an angle of 5 degrees with the horizontal. Find the force parallel to the plane resisting the motion

Answer 1

Ff = M g sin 5 where Ff is the force of friction opposing motion

Ff = .80 kg * 9.80 m/s^2 * .087 = .682 N

(note sin θ = θ 5 / 57.3 = .087 for angles less than about 10 deg)