JEE Main Physics question
A body of mass 4 kg is moving with momentum of 8 kg-ms⁻¹. A force of 0.2 N acts on it in the direction of motion of the body for 10 s. The increase in KE is
Answer: (C)
Solution
Initial velocity u = p/m = 8/4 = 2 ms⁻¹. a = F/m = 0.2/4 = 0.05 ms⁻². v = u+at = 2+0.5 = 2.5 ms⁻¹. ΔKE = ½(4)(2.5²−2²) = 2(6.25−4) = 4.5 J.