A body of mass m1 moving with an unknown velocity of \({v_1}\hat i\;\), undergoes a collinear collision with a body of mass m2 moving with velocity \({v_2}\hat i\). After the collision, m1 and m2 move with velocities of \({v_3}\hat i\;{\rm{and}}\;{v_4}\hat i\) respectively. If m2 = 0.5m1 and v3 = 0.5v1, then v1 is:

• A. \({{\rm{v}}_4} - \frac{{{{\rm{v}}_2}}}{2}\)
• B. v4 – v2
• C. \({{\rm{v}}_4} - \frac{{{{\rm{v}}_2}}}{4}\)
• D. v4 + v2