Question

A $2kg$ block moving with $10m/s$ strikes a spring of constant ${\pi }^{2}N/m$ attached to $2kg$ block at rest kept on smooth floor. The velocity of the rear $2kg$ block after it separates from the spring will be

• A. $0m/s$
• B. $5m/s$
• C. $10m/s$
• D. $7.5m/s$

Answer 1

Answer: (B)

$5m/s$

Applying conservation of linear momentum, we get

$mV=m{V}^{\prime }+m{V}^{\prime }$

$\Rightarrow$ $mV=2m{V}^{\prime }$

$\Rightarrow$ $V^{\prime }=\frac{V}{2}=5m/s$