A 275 kg piano slides 4.4 m down a 30° incline and is kept from accelerating by a man who is pushing back on it parallel to the incline (Fig. 6-36). The effective coefficient of kinetic friction is 0.40. a)Calculate the force exerted by the man. b)Calculate the work done by the man on the piano. (c) Calculate the work done by the friction force. (d) What is the work done by the force of gravity? (e) What is the net work done on the piano?