Question

Ball 1, with a mass of 140 g and traveling at 12 m/s , collides head on with ball 2, which has a mass of 350 g and is initially at rest.

What is the final velocity of the ball 1 if the collision is perfectly elastic?

What is the final velocity of the ball 2 if the collision is perfectly elastic?​

What is the final velocity of the ball 1 if the collision is perfectly inelastic?

What is the final velocity of the ball 2 if the collision is perfectly inelastic?

Answer 1

apply momentum conservation

case 1 perfectly elastic

apply momentum conservation + energy conservation

formula

so  

velocity of the ball 1   = -5.143 m/s

velocity of the ball 2 = 6.857 m/s

case 2

perfectly inelastic only apply momentum conservation

both ball will have same speed in htis case as they stick together

Pi = Pf  

140*10^-3 *12 +350*10^-3*0 = ( 140+350)*10^-3* Vc

Vc =140*12 / ( 140+350) =3.42857143 m/s

final velocity of the ball 1 = final velocity of the ball 2 = 3.42857143 m/s

let me know in a comment if there is any problem or doubts​