Question

a labourer lifts 100 stone to a height of 6m in two minute.if mass of each stone be one kilogram, calculate the average power

Answer 1

total mass = 1 kg x 100 = 100 kg
height = 6 m
time taken = 2 x 60 sec = 120 s
work done = mass x g (acceleration due to gravity ) x height
work done = 100 x 9.8 x 6
= 5880 J
average power = work done / time taken
= 5880 / 120
= 49 W

Answer 2

g=10m/s2
=>total mass=1×100
=>100kg
=>Height=6m
=>work done=mgh
100×10×6=6000J
Time=2 minutes=2×60=120 sec
=>Average power=work done/time taken
=6000/120
=50W.Ans