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## Homework Statement

A pulley system has an efficiency of 76.9%. The acceleration of gravity is 9.81 m/s^2. How much of the rope must be pulled in if a force of 620 N is needed to lift a 52 kg desk 2.32 m?

## Homework Equations

Force = ma

Work = force * distance

## The Attempt at a Solution

Because the efficiency is 76.9%, I divided 620 N by .769 to find the amount of force that the pulley system would actually have to do. (806 N). I then found the amount of work required to lift the desk without the pulley system. 52 kg * 9.81 m/s^2 * 2.32 m = 1182.87 J

To find the distance the rope has to be pulled in, I used the work formula.

1182.87 J = 806 N * (distance)

distance =1.47 m

Pulley problems have never been my forte and I'm not sure if my attempt at this problem was right. Any help would be much appreciated!