Question

Block A in the figure is released from the rest when the extension in the spring is 0. The downward displacement of the block before coming to momentary rest will be

• A. Mg/2k
• B. Mg/k
• C. 2Mg/k
• D. 4Mg/k

Answer 1

The correct option is B Mg/k

Let extension be $x$..
By energy conservation:
$\frac{1}{2}k{x}^2=Mgx/2$
$x=\frac{Mg}{k}$
$\therefore$Maximum displacement =$\frac{Mg}{k}$