Question

Two blocks of masses $10kg$ and $4kg$ are connected by a spring of negligible mass and placed on a frictionless horizontal surface. An impulse gives a velocity of $14m{s}^{-1}$ to the heavier block in the direction of the lighter block. The velocity of the centre of mass in $m{s}^{-1}$ is $2n$ , then $n=$

Answer 1

Answer: 5

${\text{v}}_{\text{CM}}=\frac{{\text{m}}_1{\text{v}}_1+{\text{m}}_2{\text{v}}_2}{{\text{m}}_1+{\text{m}}_2}$
$\frac{10\times 14+4\times 0}{10+4}=\frac{10\times 14}{14}=10m{s}^{-1}$ $=2n\Rightarrow n=5$