One coolie takes 1min to raise a box through a height of `2m`. Another one takes `30s` for the same job and does the same amount of work. Which one of the two has greater power and which one uses greater enegy?

Explanation

Power of the first coolie `=(Work)/(Time)`
`=(MxxgxxS)/(t)=(Mxx9.8xx2)/(60)Js^-1`
Power of the second coolie is
`(Mxx9.8xx2)/(30)Js^-1=2((Mxx9.8xx2)/(60))Js^-1`
`=2xx` Power of the first coolie
So, the power of the second coolie is double that of the first one.
Both the coolies spend the same amount of energy.
Alternative method: We know that `W=Pt`
For the same work, `W=P_1t_1=P_2t_2`
or `P_2/P_1=t_1/t_2=(1min)/(30s)=2` or `P_2=2P_1`