How is the power related to the speed at which a body can be lifted? How many kilograms will a man working at the power of 100 W, be able to lift at constant speed of 1 m s–1 vertically? (g = 10 m s–2)

Soln:

Power = work/time work=force x displacement force = mass x acceleration acceleration=velocity/time

Therefore

Power= velocity×mass× displacement

time × time

Here Power,P=100W velocity,v=1m/s since time,t=1s displacement, s=1m acceleration,a=10m/s

From equation P=m×a×s

t 100=m×10

m=10