Q. A particle is acted upon by a force $F\ $which varies with position $x\ $as shown in figure. If the particle at $x = 0$ has kinetic energy of 25 J, then the kinetic energy of the particle at $x = 16\ m$ is
A) 45 J
B) 30 J
C) 70 J
D) 135J
Explanation
(a) Work done=area between the graph force displacement curve and displacement
$W = \frac{1}{2} \times 6 \times 10 - 5 \times 4 + 5 \times 4 - 5 \times 2$
$W = 20\ J$
According to work energy theorem
$\mathrm{\Delta} = K_{E} = W$
${K_{E}}_{f} = W + \mathrm{\Delta}K$
=20+25
=45J
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.