Q. The potential energy of a certain spring when stretched through a distance $s$ is 10 J. The amount of work (in joule) that must be done on this spring to stretch it through additional distance $s$ will be
A) 30
B) 40
C) 10
D) 20
Explanation
(a) $U = \frac{1}{2}ks^{2} = 10\ J$
$U^{'} = \frac{1}{2}k(s + s)^{2} = 4\left( \frac{1}{2}ks^{2} \right) = 40$ J
$W = U^{'} - U = 40 - 10 = 30\ J$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.