Physics 8B
posted by HELP .
A 280 electric motor is 90% efficient, meaning that 90% of the energy supplied to it ends up as mechanical work.
If the motor lifts a 210 weight at 3.5 , how much current does it draw?
Express your answer using two significant figures.
I= ? Amps

No units are given; therefore, I'll have to make some assumptions:
Wt = 210 Newtons @ 3.5m/s.
280 Volt motor
Power = 210 * 3.5m/s = 735 Watts output
Power Input = Po / 0.9 = 735/0.9 = 817
Watts.
P = V*I,
I = P / V = 817 / 280 = 2.9 Amps.