Question

A labourer weighing 70kgs climbs 11 step of a stair case each 0.21 m height in 1.4. Find the power in watt and the Horse Power (g = 9.8ms^-2)

Answer 1

Mass of labourer m = 70kg

Total height of stair case = 11 × 0.21

h = 2.31m

Time taken to climb = 1.4 seconds, g = 9.8ms^-2

∴ Work done, W = mgh

= 70 × 9.8 × 2.31

= 1585 J.

∴ Power P = \(\frac{w}{t}\) = \(\frac{1585}{1.4}\)= 1132 W

But, 1 HP = 746 Watts

∴ Power in Horse power 

= 1.517 HP.