Q. When a spring is stretched by $2\ cm$, it stores $100\ J$ of energy. If it is stretched further by $2\ cm$, the stored energy will be increased by
A) $100\ J$
B) $200\ J$
C) $300\ J$
D) $400\ J$
Explanation
(c) $100 = \frac{1}{2}kx^{2}$ [Given]
$W = \frac{1}{2}k\left( x_{2}^{2} - x_{1}^{2} \right) = \frac{1}{2}k\left\lbrack (2x)^{2} - x^{2} \right\rbrack$
$= 3 \times \left( \frac{1}{2}kx^{2} \right) = 3 \times 100 = 300\ J$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.