Centre of Mass 1 Question 9
9. Two blocks of masses $10 kg$ and $4 kg$ are connected by a spring of negligible mass and placed on a frictionless horizontal surface. An impulse gives a velocity of $14 m / s$ to the heavier block in the direction of the lighter block. The velocity of the centre of mass is
(2002, S)
(a) $30 m / s$
(b) $20 m / s$
(c) $10 m / s$
(d) $5 m / s$
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Answer:
Correct Answer: 9. (c)
Solution:
$$ \begin{aligned} & \longrightarrow v _1=14 m / s \end{aligned} $$
$$ \begin{aligned} & v _{CM}=\frac{m _1 v _1+m _2 v _2}{m _1+m _2}=\frac{10 \times 14+4 \times 0}{10+4}=\frac{140}{14}=10 m / s \end{aligned} $$
