Coefficient of restitution and velocity

[Parikshit M]

We know that the ratio of velocity of separation to the velocity of approach of two bodies in a head on collision is called coefficient of restitution .Is there no possibility that the velocity of separation is quite larger than that of approach? or vice versa? can't the ratio be more than 1 or less than 0 ?

 

[Doc Al]

Is there no possibility that the velocity of separation is quite larger than that of approach? or vice versa?

Those are two very different situations. For example, if the bodies stick together (a perfectly inelastic collision) the separation velocity will be zero.

What do you think a coefficient of restitution greater than one would imply?

 

[Parikshit M]

Those are two very different situations. For example, if the bodies stick together (a perfectly inelastic collision) the separation velocity will be zero.

What do you think a coefficient of restitution greater than one would imply?

It would imply that the velocity of separation is greater than that of approach .

 

[bhillyard]

And what of the energy?

 

[Doc Al]

It would imply that the velocity of separation is greater than that of approach .

Well, yes. But what does that imply as far as energy goes?

 

[Parikshit M]

energy increases?.. due to increase in velocity , kinetic energy increases and hence final kinetic energy will be greater.So does that mean mechanical energy is not conserved?

 

[Doc Al]

So does that mean mechanical energy is not conserved?

That's correct. A collision where the kinetic energy is greater after the collision than before would be an example of a superelastic collision--mechanical energy is not conserved. Some internal energy of the system must have been converted to mechanical kinetic energy. Not the typical collision between two objects.

 

[Parikshit M]

thanks a lot my books never said anything about super elastic collisions , delighted ! thanks again