A5.8 × 104-watt elevator motor can lift a total weight of 2.1 × 104 newtons with a maximum constant speed of
(1)0.28 m/s
(2)0.36 m/s
(3)2.8 m/s
(4)3.6 m/s

Power is defined as the rate at which work is done upon an object. Like all rate quantities, power is a time-based quantity. Power is related to how fast a job is done. Two identical jobs or tasks can be done at different rates - one slowly or and one rapidly.

P = Fv

Where P is the power

F is the weight

V is the average velocity

V = P/F

V = (5.8 x 10^4 W)/ (2.1 x 10^4 N)

V = 2.8 m/s

Considering the definition of power, the correct answer is option (3): A 5.8×10⁴ watt elevator motor can lift a total weight of 2.1×10⁴ newtons with a maximum constant speed of 2.8 m/s.

Power can be defined as how fast work is done or how quickly energy is used.

Power can be calculated as a function of speed. So mathematically, power is the result of multiplying force times speed:

P = F×v

Where

This means that the same power value can be obtained by moving very little weight very fast, or moving a lot of weight very slowly.

In this case, you know:

Replacing:

5.8×10⁴ W= 2.1×10⁴ N × v

Solving:

v= 2.8 m/s

Finally, the correct answer is option (3): A 5.8×10⁴ watt elevator motor can lift a total weight of 2.1×10⁴ newtons with a maximum constant speed of 2.8 m/s.

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