Predicting types of collisions

[crudux_cruo]

I've been working through Chapter 9 of Fundamentals of Physics (Center of Mass and Linear Momentum) and while I think I generally understand the different types of collisions, I notice that all of the problems state (or heavily imply) the type of collision after it has happened.

Does predicting the type of collision generally require knowing more advanced topics like material science, or am I missing something fundamental from the textbook?

 

[Ibix]

Welcome to PF.

What do you mean by "type of collision"? Elastic vs inelastic, or something else?

 

[crudux_cruo]

Welcome to PF.

What do you mean by "type of collision"? Elastic vs inelastic, or something else?

Thanks!

And yes, elastic vs inelastic. From what I understand all real life collisions are some degree of inelastic, with elastic collisions being useful mainly as an approximation.

Assuming I understand that correctly, I wanted to know what physically determined that 'degree of inelasticity'. I apologize if I am using improper or imprecise language here.

 

[Ibix]

Yes, all realistic collisions involve some energy loss. I think you are correct that predicting the degree of energy loss from first principles is a hard problem. The number describing the degree of elasticity is the coefficient of restitution, which you can look up if you want. As far as I'm aware you usually just measure it for any given collision.

 

[crudux_cruo]

I appreciate the succinct response. I'm amazed I couldn't find it with a simple google search, but after doing some reading on COR the things are a fair bit more intuitive. I'm sure I'll confuse myself with it in a day or two though.

 

[Ibix]

Glad to help - sometimes it's just knowing the term to look for.