Question

An ideal spring with spring constant $k$ is hung from the ceiling and a block of mass $M$ is attached to its lower end. The mass is released with the spring initially unstretched. Then the maximum extension in the spring is (Given acceleration due to gravity $=g$)

• A. $\frac{4Mg}{k}$
• B. $\frac{2Mg}{k}$
• C. $\frac{Mg}{k}$
• D. $\frac{Mg}{2k}$

Answer 1

Answer: (B)

$\frac{2Mg}{k}$

The potential energy $=\frac{1}{2}k{x}^2$

here, $P.E=Mgx$ .Thus , $Mgx=\frac{1}{2}k{x}^2$

$\therefore x=\frac{2Mg}{k}$