Question

A man of 50 kg mass climbs a stair of 20 steps in 40 second. If each
step has 25 cm height, calculate power of the man. [Ans: 62.25 W]​

Answer 1

Given :

• Mass of man = 50 kg
• No of steps = 20
• Time taken = 40 s
• Height of each step= 25 cm=0.25 m

To find :

• Power of the man

Solution :

⇒ The total height of the man = No of steps x Height of each step

⇒ The total height of the man = 20 x 0.25

⇒ The total height of the man = 5 m

The work done by the man will be equal to its potential energy.

Hence,

$\implies\mathtt{W = mgh}$

here ,

• m = mass
• g= acceleration due to gravity
• h = height

⇒ W = 50 x 10 x 5

⇒ W = 2500 J

As per the formula,

$\implies\mathtt{P = W/t }$

here,

• P = power
• W = work
• t = time

⇒ P = 2500 / 40

⇒ P = 62.5 W

The power of the man is 62.25 W.