Question

One end of a block of mass $m=3kg$ placed on a horizontal smooth surface is attached with a spring of force constant $100N/m$. Other end of the spring is attached to a wall as shown in figure. Suddenly a constant horizontal force of $10N$ starts acting on the block towards right and as a result the block starts moving towards right. Find energy (in $J$ ) stored in the spring when the block stops for the first time (initially spring was in natural length).

Answer 1

Answer: 2.00

WET
$10x_{\max }-\frac{100}{2}{x}_{\max }^2=0$
$x_{\max }=\frac{20}{100}=\frac{1}{5}$ metre
$E_{\text{stored in spring }}=\frac{1}{2}\times 100\times {\left(\frac{1}{5}\right)}^2$
$\Rightarrow 2$ joule