Question

A man whose weight is 500 N moves up 15 steps each of height 15 cm in 40 seconds of time . Calculate the power used in climbing those stairs

Answer 1

height = 15 × 15 cm = 225 cm = 2.25 m
time = 40 sec

workdone by man = F.h
= 500 × 2.25 j

power = work done /time taken
= 500 × 2.25/40
=12.5 × 2.25 watt
=28.125 watt

Answer 2

height of 1 step = 15 cm
Height of 15 steps = 15 × 15 cm = 225 cm
= 2.25 m
time = t = 40 sec

work done by man = F x s
= 500 x 2.25
= 1125 Joules

Power = Work done / time = 1125 / 40 =28.125 Watts


power = work done /time taken
= 500 × 2.25/40
=12.5 × 2.25 watt
=28.125 watt