Two particles of masses m1 and m2 in projectile motion have velocities ¯¯¯v1 and ¯¯¯v2 respectively at time t=0. They strike at time t0 and their velocities become ¯¯¯¯v′1 and ¯¯¯¯v′2 at time 2t0 while still moving in air. The value of
∣∣(m1¯¯¯¯v′1+m2¯¯¯¯v′2)−(m1¯¯¯v1+m2¯¯¯v2)∣∣ is :