Aworker is using a pulley to lift a 33-kilogram crate. if he applies a force of 129 newtons, the crate is lifted 16.5 meters above the ground and the displacement of the rope is 33 meters. what is the efficiency of the pulley? (given: g = 9.8 meter/second2)

79.8 %

Explanation:

The energy in input to the system is equal to the work done by the worker, so:

where

F = 129 N is the force applied

d = 16.5 m is the displacement of the rope

Substituting,

The output work of the system is the gravitational potential energy gained by the crate, so

where

m = 33 kg is the mass of the crate

g = 9.8 m/s^2 is the acceleration of gravity

is the gain in height of the crate

Substituting,

So, the efficiency of the pulley is

So, 79.8 %.