Q. If a spring extends by $x$ on loading then the energy stored in the spring is (if T is the tension and $k$ is the force constant of the of the spring).
A) $\frac{T^{2}}{2x}$
B) $\frac{T^{2}}{2k}$
C) $\frac{2k}{T^{2}}$
D) $\frac{{2T}^{2}}{k}$
Explanation
(d) In equilibrium, $T = mg$
Work done$= mg = mgx = \frac{1}{2}kx^{2}$
or $x = \frac{2mg}{k} = \frac{2T}{k}$
Energy stored$= mgx = Tx$
$= T \times \frac{2T}{k} = \frac{2T^{2}}{k}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.