3 m/s ના વેગથી m_1 દળનો પદાર્થ સ્થિર રહેલા

If target is at rest then final velocity of bodies are
${v_1} = \left( {\frac{{{m_1} - {m_2}}}{{{m_1} + {m_2}}}} \right)\;{u_1}$ …(i) and ${v_2} = \frac{{2{m_1}{u_1}}}{{{m_1} + {m_2}}}$…(ii)
From (i) and (ii) $\frac{{{v_1}}}{{{v_2}}} = \frac{{{m_1} - {m_2}}}{{2{m_1}}} = \frac{2}{5}$$⇒$$\frac{{{m_1}}}{{{m_2}}} = 5$