The efficiency of an electric motor is 20 %. When lifting a body 500 J of energy are wasted. What is the useful work done by the motor?

Question

please and thank u!

Answer 1

1/5 Effort=500
Effort=2500J
useful work=2500-500=???

Answer 2

sir, the answer is supposed to be 125?? is there something wrong

Answer 3

Eff. = Eo/Ei = 0.2.
Eff. = Eo/(Eo+500) = 0.2.
Eo = 0.2Eo+100,
0.8Eo = 100,
Eo = 125J. = Energy out = Useful work.

Answer 4

HENRY THANK YOU MAN

Answer 5

Thanks a lot, Terrific information.
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