Question

A man carrying a bag of total mass 25 kg climbs up to a height of 10 m in 50 seconds. Calculate the power delivered by him on the bag.

Answer 1

Mass of the bag = 25 kg ; Height ‘h’ = 10 m

Acceleration due to gravity g = 9.8 m/s² 

The P.E. of the man = mgh = 25 × 9.8 × 10 = 2450 J 

The work done by the man is equal to the P.E. possessed by the man. 

∴ The work done by the man (W) = 2450 J ; Time (t) = 50 sec. 

∴ Power delivered by the man on the bag = \(\frac{W}{t}=\frac{2450\,J}{50\,sec}\) = 49 watts