# A body of mass 3 kg is under a constant force which causes a displacement s in metres in it, given by the relation $S=\frac{ 1}{ 3}{t^2}$ , where t is in seconds. Work done by the force in 2 seconds is:-
( A ) $\frac {3} {8}{J}$
( B ) $\frac {5} {19}{J}$
( C ) $\frac {8 }{3}{J}$
( D ) $\frac {19} 5{J}$