Question

An elevator ascends from the ground floor to the 10th floor, a height of 41 m, in 35 s. If the mass of the elevator and passengers is 840 kg, what’s the power necessary to lift the elevator? (Your answer is greater than the actual power needed because elevators are counterweighted, thus reducing the work the motor needs to do.)

Answer 1

Answer:

9.84 kW

Explanation:

we can solve this by using definitions and formulas for power & work done

work done for listing the lift with the people (W)

Here lift work against the gravity

Work done =  Force * distance

                   = mass*g*height

                   = 840 * 10 * 41              (assume g=10 ms⁻²)

                   = 344.4  kJ

Power means the rate of the work done

$power=\frac{work.done}{time}\\ = \frac{344.4 kJ}{35}\\ =9.84 kW$