A 45 kg block of ice slides down a frictionless incline l.5 m long and 0.91 m high, a worker pushes up against the ice, parallel to the incline, so that the block slides down at constant speed.

(a) Find the magnitude of the worker's force. How much work is done on the block by?

(b) The worker's force,

(c) The gravitational force on the block,

(d) The normal force on the block from the surface of the incline, and

(e) The net force on the block?