Elastic and Perfectly Elastic Collisions

HollowGrowl SG

hi there, does anyone know whats the difference between

-elastic/(inelastic) collisions
- perfectly elastic/(inelastic) collisions?

was wondering what the answer was when i found this intriguing question on another forum =x

eagle SG

perfectly elastic means there's no energy loss after collision

elastic and inelastic means there's some energy loss

However, in both cases, there's still conservation of momentum

In addition, coefficient of restitution for perfectly elastic collisions is 1, perfectly inelastic is 0, and all other collisions are somewhere between 0 and 1.

I think this is in A level phyiscs...

wee_ws SG

Hi,

From H2 Physics syllabus:

1. Knowledge of the concept of coefficient of restitution is not required.

2. Candidates should be able to recognise that, for a perfectly elastic collision between two bodies, the relative speed of approach is equal to the relative speed of separation.

Thanks!

Cheers,
Wen Shih

HollowGrowl SG

perfectly elastic means there's no energy loss after collision

elastic and inelastic means there's some energy loss

However, in both cases, there's still conservation of momentum

In addition, coefficient of restitution for perfectly elastic collisions is 1, perfectly inelastic is 0, and all other collisions are somewhere between 0 and 1.

I think this is in A level phyiscs...

ya i think its in chapter 2 or 3 of this year's syllabus.

Thanks for the replies

Audioboxing SG

Adding to what that has been said, there can never be a inelastic collision where kinetic energy is perfectly conserved...

In fact, since elastic collisions conserve energy of the center of mass, there is no difference between a perfectly elastic collision and an elastic collision. Except the choice of words. :D

You may say that maybe some kinetic energy is lost, but then if it is lost, the total energy is no longer the same, hence it is not conserved.

As long as the sum of forces is zero, momentum is conserved.