Question

A man whose mass is 50 kg moves up 15 steps each of height 15 cm in 45 seconds of time. Calculate the power used in climbing those stairs. (g = 10 m/s² )

Answer 1

Given 

Mass of Body (m) = 50 Kg, 

Time (t) = 45s, 

Height of each step = 15 cm, 

Acceleration due to gravity (g) = 10 m/s² . 

Now 

Weight = mg = 50×10 = 500N 

Height of staircase = 15 x \(\frac{15}{20}\) = 2.25 m

(∵ 1m = 100 cm)

Power = \(\frac{work}{Time}\) = \(\frac{mgh}{t}\)

⇒Power = \(\frac{500\times2.25}{45}\) = \(\frac{1125}{45}\) =25

Power = 25 Watt 

Power used in climbing stairs = 25 W