Question

A 1.7 × 10
3
kg elevator carries a maximum
load of 876.7 kg. A constant frictional force
of 4.3 × 10
3
N retards the elevator’s motion
upward.
What minimum power must the motor deliver to lift the fully loaded elevator at a constant speed 3.45 m/s? The acceleration due
to gravity is 9.81 m/s
2
.
Answer in units of kW

Answer 1

First, let's define power, so we know what we have and what we will need to determine. \[P = F \cdot v\]
We are given the velocity at which the elevator travels, now all we need to do it determine the forces involved. I spot only two, gravitation and friction. \[F = F_g + F_f = m \cdot g + F_f\]