A body of mass m_1 moving with an unknown velocity of v_1 i, undergoes a collinear collision with a body of mass m_2 moving with a velocity v_2 i.…

A body of mass $\displaystyle m_1$ moving with an unknown velocity of $\displaystyle v_1 \hat{i}$, undergoes a collinear collision with a body of mass $\displaystyle \mathrm{m}_2$ moving with a velocity $\displaystyle v_2 \hat{i}$. After collision, $\displaystyle \mathrm{m}_1$ and $\displaystyle \mathrm{m}_2$ move with velocities of $\displaystyle v_3 \hat{i}$ and $\displaystyle v_4 \hat{i}$, respectively. If $\displaystyle \mathrm{m}_2=0.5 \mathrm{~m}_1$ and $\displaystyle v_3=0.5 v_1$, then $\displaystyle v_1$ is :