Q. A block of mass $M$ is attached to the lower end of a vertical spring. The spring is hung from a ceiling and has force constant value $k$. The mass is released from rest with the spring initially unstretched. The maximum extension produced in the length of the spring will be
A) $1\ Mg/k$
B) $2Mg/k$
C) $4\ Mg/k$
D) $Mg/2k$
Explanation
(b) Work done in max extension = stored $P.E.$
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$\Rightarrow Mg \times x = \frac{1}{2}kx^{2}$
$\Rightarrow x = \frac{2Mg}{k}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.