[masraum]

Originally Posted by snowman

Only problem here is that the heavy particle is NOT much larger than the light particle. Much heavier imply s a factor of at least 10. In your case likely a factor of 1000 or more. Also the collision is not totally inelastic in your case, because energy MUST be conserved. The lighter ball MUST end up going faster than the heavy ball. Your calcs are probably what a real item would do (elastic}, but we are dealing with ideal (inelastic) balls here.

Anyone can do the math, its the setup that separates the men from the boys.

The equations that I used were correct and were setup correctly. I just did the math wrong. I guess that's what I get for working on this when I was tired.

When I re-did the math I got the same thing that Steve/sjf911 got in his simple, short post

Originally Posted by sjf911

IIRC, it should be 1/3 of V1 for M1 and 4/3 of V1 for M2. So 3.3333mph and 13.3333mph.

My equations were for an elastic collision and did take conservation of energy and momentum into account.

before collision -- mv + mv = mv + mv -- after collision -- momentum
and
before collision -- 1/2 mv^2 + 1/2 mv^2 = 1/2 mv^2 + 1/2 mv^2 -- after collision -- KE

so, the big ball would be going 3.333 mph after the collision and the small ball would be going 13.333 mph after the collision. Not really quite double the speed of the big one.