Assertion: A quick collision between two bodies is more violent that show collision , even when initial and final velocity are identical.
Reason: The rate of change of momentum determine that force is small or large.

Assertion: Collisionn between two billiard's ball are inelastic Reason: Momentum remains conserve during the collision.

Assertion: During head on collision between two bodies let Deltap_1 is change in momentum of first body and Deltap_2 the change in momentum of the other body, then Deltap_1=Deltap_2 . Reason: Total momentum of the system should remain constant.

Assertion : In case of elastic collision between two objects , speed of approach is same as speed of separation . Reason : In case of elastic collision between two objects , linear momentum of the system remains conserved .

Assertion: In a elastic collision (e = 1) between two bodies, conservation of kinetic energy holds true. i.e., (K_(1) + K_(2))_(i) = (K_(1) + K_(2))_(f) . Reason: Conservation of momentum holds true i.e., (P_(1) + P_(2))_(i) = (P_(1) + P_(2))_(f) .

Assertion: In an elastic collision of two bodies , the momentum and energy of each body is conserved. Reason: If two bodies stick to each other , after colliding , the collision is said to be perfectly elastic.