# We can only calculate Perfectly elastic/Perfectly inelastic collisions?

#### hellocubed

##### Full Member
I'm just confirming that the MCAT only expects us to be able to calculate perfectly elastic and perfectly inelastic equations?

I was wondering how momentum conservation of a highly deforming car collision could be calculated, and then I remember- oh yeah, that's pretty much impossible with what I know.

Also, is all elastic collision considered to be perfectly elastic?
I can't think of it being any other way without just being labeled as inelastic...

Ahhh, nvm.

#### dmf2682

##### Membership Revoked
Removed
I'm just confirming that the MCAT only expects us to be able to calculate perfectly elastic and perfectly inelastic equations?

I was wondering how momentum conservation of a highly deforming car collision could be calculated, and then I remember- oh yeah, that's pretty much impossible with what I know.

Also, is all elastic collision considered to be perfectly elastic?
I can't think of it being any other way without just being labeled as inelastic...

You can have something called a coefficient of restitution but if mcat asks about it, it'll probably be explained in the passage

#### MedPR

##### Membership Revoked
Removed
If they ask you to calculate a partially inelastic collision, they will have to give you some other piece of information. Anything other than perfectly elastic/perfectly inelastic requires more work but the concepts are the same.

#### milski

##### 1K member
5+ Year Member
Momentum is always conserved! It's the energy that you have to worry about, based on the collision. If you have two cars with the same mass going towards each other [in some reference frame] after the collision they will be at rest [in the same reference frame]. They might have different amount of damage and different amount of crumbling, based on how elastic the collision was and how energy was distributed, but the final velocity of each pile of junk will be 0.

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