Inelastic Collisions

There are two basic kinds of collisions in momentum: Elastic and Inelastic collisions. An Elastic collision is a collision where not only momentum is conserved, but the total kinetic energy of the system is also conserved. These will be discussed in another lesson. However, an Inelastic collision, only the momentum
of the system is conserved. Total Kinetic Energy is not conserved – some of the kinetic energy is transformed into other forms of energy during the collision.

There are two types of inelastic collisions to consider: An Inelastic Collision and a Perfectly Inelastic Collision. The difference between an inelastic collision and a perfectly inelastic collision is that in the perfectly inelastic collision, the two objects stick together after the collision. An example would be two cars that crash and lock bumpers.

In an inelastic collision, Kinetic Energy is NOT conserved…energy changes into other energies such as thermal energy or noise.

In an inelastic collision, Momentum IS conserved.- Also, in an inelastic collision, something is misshapen or lost.-

The same goes for Perfectly Inelastic Collisions, KE is NOT conserved, and Momentum IS.

An example of a Perfectly Inelastic Collision would be a ballistic pendulum. This is a device used to measure the speed of a moving object. The moving object with a mass m is fired into a hefty chunk of wood (usually) with a mass M. The chunk of wood is suspended from the ceiling like a pendulum. When mass m is fired into mass M,
mass M swings back on its pendulum-swing, creating a maximum height h.
So to sum up, it would be good to
know this table:

 

Type of Collision

Momentum is Conserved

Kinetic Energy is Conserved

Elastic

Yes

Yes

Inelastic

Yes

No

Perfectly Inelastic

Yes

No