Question

Two blocks $A$ and $B$ are hanging across an ideal pulley as shown in the figure. Mass of $A$ is $m$ and mass of $B$ is $2m$. $A$ is raised by $h=18cm$ and released to fall freely under gravity, while $B$ is resting on ground. Sometime after, there is jerk in the string, due to which the maximum height (in $cm$ ) attained by block $B$ is

Answer 1

Answer: 6

$mgh=\frac{1}{2}m{v}^2$
$\Rightarrow v=\sqrt{2gh}$

Now, $2mg{l}^{\prime }-mg{l}^{\prime }=\frac{1}{2}(3m){\left(\frac{v}{3}\right)}^2$
$\Rightarrow g{l}^{\prime }=\frac{gh}{3}=\frac{h}{3}$