A man of mass 50kg ascends a flight of stains 5m high in 5 seconds. If acceleration due to gravity is 10ms−² the power expended is

A. 100w
B. 200w
C. 400w
D. 500w

Correct Answer:

Option D – 500w

Explanation

Power is the time rate of doing work

i.e power = energy/time

Since energy = mgH

∴ power = mgH/t

= 50×10×5/t

= 500W