Question

An electric motor has a power rating of 1.60 kW and operates at 75% efficiency. The amount of work that it can do in 1.0

hrs is__ x10^6J. Give your answer with the correct number of sig digs and do not include units)

Answer 1

Answer: 4.3 x 10^6 J

Explanation: P= W/t so W=Pt.

The power here is 1600 J/s (1.6 kW) and the time is 3600s (1 hour x 60 mins x 60 seconds).

1600x3600 = 5760000 J (5.76 x 10^6 J).

Efficiency = Eout/Ein so Eout = Efficiency x Ein.

(0.75) x (5.76 x 10^6) = 4.3x10^6 J.