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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