Condition Of Collision For Moving Particles

Two particles P and Q are projected from two points in the same plane as shown. Find the condition for collision of two paricles.

During inclined collision of two particle

Consider elastic collision of a particle of mass m moving with a velocity u with another particle of the same mass at rest. After the collision the projectile and the struck particle move in direction making angles theta_(1) and theta_(2) respectively with the initial direction of motion. The sum of the angles. theta_(1)+theta_(2) , is

In a one-dimensional collision between two particles, their relative velocity is vecv_(1) before the collision and vecv_(2) after the collision