When objects collide without being permanently deformed and without generating heat, it is an elastic collision.

Billiard balls colliding is one example of elastic collisions (sort of). Momentum is conserved in elastic collisions.

When the objects are distorted in a collision and the collision generates heat, it is said to be an inelastic collision.

Momentum is still conserved in inelastic collisions. Momentum is always conserved in all collisions.

Jaws (mass = 3000 kg) swims at a velocity of 2 m/s and swallows Spongebob Squarepants© (200 kg) in one gulp. If “bob” is motionless before becoming lunch, what is the final velocity of Jaws + “bob”?

How would the situation be different if Spongebob® were swimming toward Jaws at 10 m/s?

A 1850 kg limo stopped at a traffic light is struck from the rear by a compact car with a mass of 975 kg. The bumpers lock. If the compact car was moving at a velocity of 22.0 m/s north before the collision, what is the velocity of the two car system after the collision?

Momentum is conserved in all collisions. In a perfectly elastic collision, kinetic energy is conserved also.

A 0.015 kg marble moving to the right at 0.225 m/s makes an elastic head-on collision with a 0.030 kg marble moving to the left at 0.180 m/s. After colliding, the less massive marble moves to the left at 0.315 m/s. Assume that neither marble rotates before or after the collision and that both marbles are moving on a frictionless surface. What is the velocity of the 0.030 kg marble after the collision?

Using the velocity just calculated, see if kinetic energy is conserved. (To confirm if the collision is elastic.)

In a perfectly inelastic collision, the objects that make contact stick together and kinetic energy is not conserved. Some energy is lost in the deformation of the objects and in the productionof heat and sound.

Look at the limo problem again: Is kinetic energy conserved?

Two clay balls collide head-on in a perfectly inelastic collision. The first ball has a mass of 0.500 kg and an initial velocity of 4.00 m/s to the right. The mass of the second ball is 0.250 kg and it has an initial velocity of 3.00 m/s to the left. What is the final velocity of the composite ball of clay after the collision? What is the decrease in kinetic energy during the collision?

Most collisions are neither perfectly elastic nor perfectly inelastic.

When objects collide that are not moving parallel to each other, vector analysis is used to find the resulting momentum.

The momentum along the x-axis must be conserved, and the momentum along the y-axis must be conserved.

This is true for an exploding firecracker as well. The sum of the individual fragments will be equal to the original momentum of the firecracker.