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Two electric motors drive two elevators of equal mass in a three-story building 10 meters tall. Each elevator has a mass of 1,000 kg.


The first elevator can do this work in 5.0 seconds.


Calculate the power output of the first motor.

Verified Answer :

JcAlmighty

The answer is 19620 Watt = 19.62 kWatt

Power output (P) is work (W) divided by time (t): P = W/t

A work (W) is a product of a force (F) and a
distance (d): W = F · d

Since the force is a product of mass and
acceleration: F = m · a

then work would be: W = m · a · h

P = W/t 
W = m · a · h

P = m · a · h / t

We have:
P = ?
m = 1000 kg
a = 9.81 m/s²  (gravitational acceleration on the Earth)
h = 10 m
t = 5s

P = m · a · h / t = 1000 kg  · 9.81 m/s²  · 10 m / 5 s = 19620 Watt = 19.62 kWatt

i just did it, its 2.0x10^4W

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