A body of mass 6 kg is under a force which causes displacement in it given by `s=t^(2)/4` metre where t is time. The work done by the force in 2 s is

Options

A. 12j
B. 9j
C. 6j
D. 3j

Answer

d

Explanation

Work done= Force`xx` displacement Acceleration, `a=dv/dt=d/dt((ds)/(dt))`
`S=t^(2)/4`,
`a=d/dt[d/dt[t^(2)/4]]`
`d/dt[2t/4]=1/2`
Work done , `W=6xx 1/2xxt^(2)/4=3/4t^(2)`
`3/4 xx (2)^(2)-3J`