A 7.5-kg box is being lifted by means of a light rope that is threaded through a single, light, frictionless pulley that is at- tached to the ceiling. (a) If the box is being lifted at a constant speed of 2.0 m>s, what is the power delivered by the person pulling on the rope? (b) If the box is lifted, at constant acceleration, from rest on the floor to a height of 1.5 m above the floor in 0.42 s, what average power is delivered by the person pulling on the rope?