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 $2 m$. $A$ is raised by $h=18\, cm$ 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

$m g h=\frac{1}{2} m v^{2} $
$\Rightarrow v=\sqrt{2 g h}$

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