Assignment:
Question 1. A 400-lb piano on frictionless casters is to be pushed up a 20 ft ramp to a loading platform 3 ft above the ground. How much force is needed?
Question 2. A block weighing 250 lbs is to be raised into a wagon 30 in high by a boy who can only exert a force of 50 lbs.
(a) what is the shortest board he must use as an inclined plane when there is no friction?
(b) where a force of 20 lbs is allowed for friction?
(c) what is the efficiency in (b)?