Question

Mohan having a mass of 40 kg, runs up a staircase of 50 steps in 10s. If the height of each step is 15 cm, then what is his power? 

(Take, g = 10 m/s²) 

(a) 300 W

(b) 100 W

(c) 200 W

(d) 400 W

Answer 1

Correct option is (a) 300 W

Height of one step = 15 cm = 0.15 m

Number of steps = 50

Hence, 

height = 50 x 0.15

= 7.5 m

Change in energy of man = mgh 

= 40 x 10 x 7.5 

= 3000J

Power = Work/Time

= 3000/10

= 300 W