Question

A ball of mass $m$ is dropped from a height $h$ on a platform fixed at the top of a vertical spring, as shown in figure. The platform is depressed by a distance $x$. Then the spring constant is

• A. $\frac{mg}{(h+x)}$
• B. $\frac{mg}{(h+2x)}$
• C. $\frac{2mg(h+x)}{{{x}^{2}}}$
• D. $\frac{mg}{(2h+x)}$

Answer 1

Answer: (C)

$\frac{2mg(h+x)}{{{x}^{2}}}$

Answer 2

Hence $mg(h+x)=\frac{1}{2}k{{x}^{2}}$
$k=\frac{2mg(h+x)}{{{x}^{2}}}$