Collision summary


A collision refers to the interaction between two or more objects, during which they exert forces on each other for a relatively short period. Collisions can occur between particles, such as billiard balls or atoms, or between macroscopic objects, like cars or celestial bodies.

Types of Collisions:

  1. Elastic Collision:

    • In an elastic collision, both kinetic energy and momentum are conserved.
    • The total kinetic energy before and after the collision remains the same.
    • Elastic collisions often occur at the molecular or atomic level.
  2. Inelastic Collision:

    • In an inelastic collision, only momentum is conserved, not kinetic energy.
    • The total kinetic energy of the system decreases after the collision.
    • Inelastic collisions are common in macroscopic objects like cars.

Elastic Collision Equations:

  1. Conservation of Momentum:

    • The sum of momenta before the collision is equal to the sum of momenta after the collision.
    • For two objects: m1u1+m2u2=m1v1+m2v2
    • Where is m mass, is initial velocity, and is final velocity.
  2. Coefficient of Restitution (e):

    • It quantifies the "bounciness" of the collision.
    • e=relative velocity after collisionrelative velocity before collision
    • For a perfectly elastic collision, , and for a perfectly inelastic collision, .

Inelastic Collision Equations:

  1. Conservation of Momentum:

    • As in elastic collisions, momentum is conserved in inelastic collisions.
  2. Coefficient of Restitution (e):

    • In inelastic collisions, 0 < e < 1
    • can be used to determine the degree of deformation or "stickiness" during the collision.

Real-life Applications:

  • Road traffic accidents (inelastic collisions).
  • Particle collisions in particle accelerators (high-energy physics).
  • Billiards and other sports (elastic collisions).