# A ball with a mass of # 2 kg# is rolling at #5 m/s# and elastically collides with a resting ball with a mass of #9 kg#. What are the post-collision velocities of the balls?

##### 1 Answer

Mar 12, 2016

#### Answer:

#### Explanation:

If post collision velocities be u m/s for 1st one and v m/s for 2nd one ,then applying conservation of momentum

Now collision being elastic KE will be conserved and consequently the relative velocity of 1st object with respect to 2nd is reversed .

So

Comparing (1) and (2)

and