Question

A body of mass $m_1$ moving with a velocity $3m/s$ collides with another body at rest of mass $m_2$. After collision the velocities of the two bodies are $2m/s$ and $5m/s$, respectively, along the direction of motion of $m_1$. The ratio $\frac{m_1}{m_2}$ is

• A. $\frac{1}{5}$
• B. $5$
• C. $\frac{12}{5}$
• D. $\frac{5}{12}$

Answer 1

The correct option is B $5$

Hint: “Head-on elastic collision”

Formula used:

$P_i=P_f$

Solution:

Before collision:
$P_i=3m_1+m_2\times 0=3m_1\dots \left(i\right)$

After collision
$p_f=2m_1+5m_2\dots \left(ii\right)$

From $\left(i\right)$ and $\left(ii\right)$
$3m_1=2m_1+5m_2$

$\frac{m_1}{m_2}=5$

Find Answer :$\left(b\right)$.