JEE Main Physics question
A body of mass 6 kg is acted upon by a force which causes a displacement in it given by x = t²/4 metre, where t is the time in second. The work done by the force in 2 s is
Answer: (D)
Solution
v = dx/dt = t/2. At t = 2 s, v = 1 ms⁻¹, and the body starts from rest. By the work–energy theorem, W = − = ½(6)(1²) − 0 = 3 J.