A block of mass is pulled up a rough inclined plane of angle with the horizontal at…
PHYSICS · Multi-part · A Level · Physics · Mechanics and materials · Mechanics and materials
Problem
A block of mass m is pulled up a rough inclined plane of angle α with the horizontal at constant speed. The pulling force T is applied by a light string parallel to the plane. The coefficient of kinetic friction between the block and the plane is μk. The block is moved a distance s along the incline.
(i) Draw a labelled free-body diagram showing all the forces acting on the block while it is being pulled up the plane.
(ii) Obtain expressions for the work done, in terms of the given symbols, by (a) the tension T, (b) the component of the block’s weight along the plane, (c) the normal reaction, and (d) the force of kinetic friction during the displacement s.
(iii) Hence show that the net work done on the block is zero and explain why this result is consistent with the block moving at constant speed.