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

Question

What is the final velocity of the ball 1 if the collision is perfectly elastc? Express your answer using two significant figures Problem 10.42 Ball 1, with a mass of 120 g and traveling at 11 m/s, collides head on with ball 2, which has a mass of 300 g and is iniially at rest. m/s Submit My Answers Give Up Part B what is the final velocity ofthe ball 2 the colision is perfectly olastic? Express your answer using two significant figures elela m/s Submit My Answers Give Up Part C What is the final velocity of the ball 1 if the colision is perfectly inelastie? Express your answer using two significant figures (veh m/s Submit My Answers Glve Ua

Explanation / Answer

The general formula for the velocities after elastic collisions is

v1' = (m1-m2)v1 + 2m2v2) / (m1+m2)

v1' = (0.12 - 0.30)*11/0.42

v1' = - 4,714 m/s

v2' = (m2-m1)v2 + 2m1v1) / (m1+m2)

v2' = (0.30-0.12)*0 + 2*0.12*11) / (0.12+0.30)

v2' = 2*0.12*11/0.42 = 6,2857 m/s

The first ball bounces back with 4,714 m/s

The second ball travels into the direction of the first ball with 6,2857 m/s.

The initial momentum of the system is (120g)*(111m/s) = 1320 g*m/s

This one's a lot easier. We just need to worry about conservation of momentum. The two balls will become one ball with a mass of 120g + 300g = 420g
(420g)*v = 1320 g*m/s
v = 3.14 m/s

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