posted by Leah .
John is using a pulley to lift the sail on his sailboat. The sail weighs 150 N, and he must lift it 4.0 m.
a. How much work must be done on the sail?
b. If the pulley is 50% efficient, how much work must John do on the rope to lift the sail?
a. w = f * d = 150 * 4 = 600 Nm
b. 600 / .5 = 1200 Nm