A boy of mass 50kg runs up a staricase of 45 steps in 9s. If the height of each step is 15cm, find his power. Take `g = 10m//s^2`

Options

A. `275W`
B. `375W`
C. `475W`
D. `575W`

Answer

B

Explanation

Weight of boy,
`mg = 50 kg xx 10 m s^(-2) = 500 N`
Height of the staircase,
`h = 45 xx 15//100 m = 6.75 m`
Time taken to climb, `t = 9 s`
From Eq. (11.8),
power, P = Work done/time taken
`= (mgh)/(t)`
`(500 N xx 6.75 m)/(9 s)`
`= 375 W`.
Power is `375 W`.