Question

The graph between the resistive force F acting on a body and the position of the body travelling in a straight line 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 bodyi s 4 m, its kinetic energy would be

• A. 50 J
• B. 40 J
• C. 20 J
• D. 10 J

Answer 1

The correct option is D 10 J

Area under graph= total work by resistive force = 0.5*b*h= 0.5*4*20= 40J
$KE$ at $4m$ in ideal condition = $0.5m{v}^2$= $0.5\left(25\right)(2{)}^2=50J$
$KE$ at $4m$ in presence of friction$=50-40=10J$