An unruly demonstrator lifts a stone of mass 200 g from the ground and throuws it at his opponent. At the time of projection, the stone is 150 cm above the grond and has a speed of 3.00 m/s. Calculate the work doe by the demonstrator during the process. If it takes one second for the demonstrator tolift teh stone and throw, what horsepower does he use?

Answer

A, C, D

Explanation

`m=200g=0.2kg, h=150cm=1.5m`
`v3m/sec, t=1sec`
Total work done `=1/2mv^2=mgh`
`=(1/2)xx(0.2)xx9+(0.2)(9.8)xx(1.5)`
`=3.84J`
h.p. used `=3.84/749=(5014)xx106-3`