Question

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

Answer 1

Answer:

Given, 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

Explanation:

Answer 2

$\huge\bigstar\underline\mathfrak{Answer:-}$

Weight of boy, mg = 50kg × ${10m/s}{2}$

⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀= 500N

___________________

Height of the staircase,h = 45 × $\frac{15}{100}$ m

⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀= 6.75m

___________________

Time taken to climb, t = 9s

___________________

= $power = \frac{work \: done}{time \: taken}$

= $\frac{mgh}{t}$

= $\frac{500N \times 6.75m}{9s}$

= $375W$