Question

A ball with a mass of `23 kg` is rolling at `25 m/s` and elastically collides with a resting ball with a mass of `2 kg`. What are the post-collision velocities of the balls?

Answer 1

`v_(2a)=1,038 m/sec`
`v_(1a)=23,962 m/sec`

Explanation:

`Sigma P_b= Sigma P_a`
`Sigma P_b": sum of momentums before"`
`Sigma P_a:" sum of momentums after"`
`23*25+0=23*v_(1a)+2*v_(2a)`
`575=23*v_(1a)+2*v_(2a)`
`v_(1b)+v_(2b)=v_(1a)+v_(2a)`
`25+0=v_(1a)+v_(2a) "`
`v_(1a)=25-v_(2a)`
`575=23(25-v_(2a))+2*v_(2a)`
`575=575*v_(2a)-23*v_(2a)+2*v_(2a)`
`554*v_(2a)=575`
`v_(2a)=1,038 m/sec`
`25=v_(1a)+1,038`
`v_(1a)=25-1,038`
`v_(1a)=23,962 m/sec`