Given
Mass of Body (m) = 50 Kg,
Time (t) = 9s,
Height of each step = 15 cm,
Acceleration due to gravity (g) = 10 m/s2 .
Now
Weight = mg = 50×10 = 500N
Height of staircase = 45 x \(\frac{15}{100}\) = 6.75 m (∵ 1m = 100 cm )
Power = \(\frac{Work}{Time}\) = \(\frac{mgh}{t}\)
⇒ Power = \(\frac{500\times6.75}{9}\) = \(\frac{3375}{9}\)
Power = 375 Watt