# Physics #6 The efficiency of a pulley system is 55 percent. The pulleys are used to raise a mass of 81 kg to a height of 4.6 m. What force ?

The efficiency of a pulley system is 55 percent. The pulleys are used to raise a mass of 81 kg to a height of 4.6 m. What force is exerted on the rope of the pulley system if the rope is pulled for 18 m in order to raise the mass to the required height?

### 1 Answer

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- NCSLv 73 weeks ago
efficiency = output work / input work

0.55 = F * 18m / (81kg * 9.8m/s² * 4.6m)

F = 110 N

to two significant digits.

Hope this helps!

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