- #1

1irishman

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## Homework Statement

An 8.5 X 10^3 kg elevator is pulled up at a constant velocity of 1m/s by a 10kW electric motor.

Calculate the efficiency of the electric motor.

## Homework Equations

P=w/t

%efficiency=work out/work in X 100%

W=mgh

d=vit+1/2at^2

v=d/t

## The Attempt at a Solution

The answer in the book is 83%, but I don't understand how they got that answer. Please help.

In the meantime, this is how far I got (not too far):

vi=1m/s

m=8.5X10^3kg

vf=0