The graph between the resistive force F acting on a body and the distance covered by the body is shown in the figure. The mass of the body is 25 kg and initial velocity is 2 m/s. When the distance covered by the body is 5m, its kinetic energy would be
10 J
Initial kinetic energy of the body = 12mu2=12×25×(2)2=50J
Work = Final kinetic energy -Initial kinetic energy
Final kinetic energy = Initial energy + work done by resistive force (Area between graph and displacement axis)
(Work done by resistive force will be negative)
K. E. (at x= 4m) = 50−12×4×20=50−40=10J.
The resistive force ceases to operate after it covers 4m distance hence it's kinetic energy remains the same as at 4m