Power to lift a load
A motor lifts a 50 kg load 4 m at constant speed in 2 s. Using g = 10 m/s², what average power does it deliver?
Answer B: explanation for every choice
A
This leaves out g, using mh/t.
B
Correct. P = mgh/t = (50)(10)(4)/2 = 1,000 W.
C
2,000 J is the work done, not the power.
D
This multiplies the work by the time instead of dividing.
TakeawayPower = work/time. Lifting at constant speed: P = mgh/t.
Equation usedPower
Next question →Reviewed 2026-11-05 by a medical student. Spot an error? Report it with question ID cp60.