Question

10 buckets of water (each buckets volume=10 litres) is raised manually to a height of 10 m from ground.it takes 50 minutes for the job to be done.how much power is used?(take g as 10)

Answer 1

total volume of water =10 x 10 = 100 litres
density of water =1 kg/litre
now mass of water = density x volume
= 100 x 1 = 100 kg

potential energy =workdone by raising bucket =mgh = 100 kg x 10 m/s^2 x 10 m
=10000 joule
now ,
power = workdone /time
=10000/50= 200 j /minute
= 200/60 j /sec =10/3 watt