Elastic and inelastic collisions~

[ipodtouch]

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I wanted to get these confirmed...

For all elastic collisions:
The momentum is conserved and the E is conserved.

For all inelastic collisions:
The momentum is conserved but the E is not...


What do we call a collision where the momentum is not conserved??

 

[milski]

Non-existent. Momentum is always conserved.

 

[EnginrTheFuture]

Non-existent. Momentum is always conserved.

It's a beautiful thing

 

[chiddler]

But if you define a system in a certain way, you can have non-conserved momentum. This occurs when some outside forces are involved that changes momentum of the system.

For example, you throw two rubber balls in the air and they collide 100% inelastically, falling to the ground upon collision due to gravity.

Considering the balls only, momentum is not conserved because there is gravity and it is not part of the system. Gravity is an outside force and therefore momentum is not conserved.

 

[UrshumMurshum]

It is impossible for momentum to not be conserved, it would violate Newton's third law of motion. Although as Chiddler said the system can be defined such that outside forces detracts from your ability to use momentum conservation.

Elastic collisions entail that kinetic energy is conserved