An unruly demonstrator lifts a stone of mass 200 g from the ground and throws it at his opponent. At the time of projection, the stone is 150 cm above the ground and has a speed of 3.00 m/s. Calculate the work doe by the demonstrator during the process.

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`