Q. A block of mass $m,$ attached to a spring of spring constant $k,$ oscillates on a smooth horizontal table. The other end of the spring is fixed to a wall. The block has a speed $v$ when the spring is at its natural length. Before coming to an instantaneous rest, if the block moves a distance $x$ from the mean position, then
A) $x = \sqrt{m/k}$
B) $x = \frac{1}{v}\sqrt{m/k}$
C) $x = v\sqrt{m/k}$
D) $x = \sqrt{mv/k}$
Explanation
(c) By using conservation of mechanical energy
$\frac{1}{2}kx^{2} = \frac{1}{2}mv^{2} \Rightarrow x = v\sqrt{m/k}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.