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31 votes
16.A pulley system lifts a 78kg box a height of 15 m in 18 seconds. What is the power of thepulley system?

User Oleg Kuralenko
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1 Answer

22 votes
22 votes

Given

m: mass

m = 78kg

h: height

h = 15m

t: time

t = 18s

Procedure

Power is a physical concept with several different meanings, depending on the context and the available information. We can define power as the rate of doing work, and it is the amount of energy consumed per unit of time.

First, we need to calculate the work done, which requires the force necessary to lift the box against gravity:


\begin{gathered} W=\text{mgd} \\ W=78\operatorname{kg}\cdot9.8m/s\cdot15m \\ W=11466\text{ Nm} \end{gathered}

The power is


\begin{gathered} P=(W)/(t) \\ P=\frac{11466\text{ Nm}}{18s} \\ P=637W \end{gathered}

The power would be 637 W

User Ofir Attia
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