Question

A block of mass $1kg$ is pushed towards another block of mass $2kg$ from a $6m$ distance as shown in the figure. If just after the collision, the velocity of $2kg$ block is $4m{s}^{-1}$ , then

• A. Coefficient of restitution between the blocks is $1$
• B. Coefficient of restitution between two blocks is $1/2$
• C. Coefficient of restitution between two blocks is $1/3$
• D. Coefficient of restitution between two blocks is $1/4$

Answer 1

Answer: (A)

From conservation of linear momentum we can see that velocity of $1kg$ block just after collision is $2m/s$ leftwards.


Now relative velocity of approach = $6m/s$
and relative velocity of separation = $6m/s$
$\text{e}=\frac{\text{Relative velocity of separation}}{\text{Relative velocity of approach}}=1$