The correct option is A 4000J
Given, mass of the body, m=5kg;
Initial velocity of the body, u=0;
Force acting on the body, F=20N;
Time for which the force acts, t=10s
If a is the acceleration produced in the body,
a=Fm=205=4m/s2
Let v be the velocity of the body after 10 s.
Clearly, v=u+at=0+(4)×(10)=40m/s
Kinetic energy acquired by the body,
Ek=12mv2=12(5)×(40)2=4000J