Question

A ball with a mass of `5 kg` moving at `3 m/s` hits a still ball with a mass of `6 kg`. If the first ball stops moving, how fast is the second ball moving?

Answer 1

I found `2.5m/s`

Explanation:

We can use Conservation of Linear Momentum `p=mv` along the horizontal `x` direction so that:

`p_("before")=p_("after")`

`(5*3)+(6*0)=(5*0)+(v*6)`

`15=6v`

`v=15/6=2.5m/s`