How would you include gravity in a momentum problem?

[Rnotaria]

Say you have a big ball of mass m1 and a little ball on top of that of mass m2 (assume they are a small distance apart, like 1mm). Now let's drop these from a height of h so that the big ball will bounce off the ground and collide into the little ball in an elastic collision.

Now I know gravity would play a key role in this example but how would you perform calculations with it? I know F=p/t and momentum will not be conserved since there is an external force (gravity) so knowing this, how can you determine how high each ball will rise after the collision?

 

[phinds]

How would you start on this problem? And by the way, in reality, "bouncing off the ground" is hardly an elastic collision.

Is this a homework problem? If so, you need to put it in the homework section and use the template.

 

[Rnotaria]

This was just an example I thought of because all the problems I've done so far have pretty much been absent of external forces (such as a car collision).

 

[phinds]

This was just an example I thought of because all the problems I've done so far have pretty much been absent of external forces (such as a car collision).

OK, then I ask again. How would you start on this problem?

 

[Nugatory]

This was just an example I thought of ...

It's still a homework problem - the Homework Forums are for all such problems, whether they came to you as part of formal classwork or as self-study.

I am closing this thread, but I encourage you to start a new thread in the "Introductory Physics Homework" forum and use the template. The process there is designed for this sort of problem.