Question

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.
2.0 x 102 W
2.0 x 103 W
2.0 x 104 W
2.0 x 105 W

Answer 1

Answer:

19620 Watt = 19.62 kWatt

Explanation:

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