Question

A boy of mass 50 kg runs up a staircase of 45 steps in 9 s. if the height of each step is 15 cm , find his power take g = 10 m s-².​

Answer 1

Answer:

Explanation:

mass of body, m = 50 kg

h = 45 x15 = 675 cm = 6.75 m

t = 9 s, g = 10 m

PE = mgh = 50 x 10 x 6.75 = 3375 J

Power of the body = PE / time = Energy / time = 3375 / 9 = 375 W.

Hope it will help you

Answer 2

Answer:

375 W .

Explanation:

Weight of the boy ,

mg = 50 kg × 10 m s-² = 500 N

Height of the staircase ,

h = 45 × 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 × 6.75 m

__________________

9 s

= 375 W.

power is 375 W.