Q. The graph between the resistive force $F$ acting on a body and the distance covered by the body is shown in figure. The mass of the body is $25\ kg$ and initial velocity is $2\ m/s$. When the distance covered by the body is $4m$, its kinetic energy would be
A) $50\ J$
B) $40\ J$
C) $20\ J$
D) $10\ J$
Explanation
(d) Initial K.E. of the body $= \frac{1}{2}mv^{2} = \frac{1}{2} \times 25 \times 4 = 50\ J$
Work done against resistive force
= Area between $F$-$x$ graph $= \frac{1}{2}\ \times 4 \times 20 = 40J$
Final K.E. = Initial K.E. – work done against resistive force
$= 50 - 40 = 10J$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.