# What is the momentum and velocity of each ball after hit?

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1. Mar 27, 2016

### j doe

1. The problem statement, all variables and given/known data
A 3.50 kg ball with a velocity of 10.00 m/s collides with a stationary ball with a mass of 5.00 kg. After the collision, the first ball travels at a 42.6 degree angle from its original path, while the second ball travels at a -26.7 degree angle from the other ball's original path.

1) What is the momentum of each ball after the collision?

2) What is the velocity of each ball after the collision?

2. Relevant equations

3. The attempt at a solution
i got -1.76 m/s for the first ball and 8.24 m/s for the second ball. am i correct? and for momentum both of the balls will have a momentum of 35.00 Ns?

2. Mar 27, 2016

### andrewkirk

Show your working. Otherwise there's no way for anybody to say whether you're correct without having to do the whole problem for themselves.

3. Mar 27, 2016

### j doe

for the first ball i did [(3.50kg-5.00kg)(10.00m/s)] / (3.50kg+5.00kg) = -1.76 m/s and for the second ball i did [2(3.50kg)(10.00m/s)] / (3.50kg+5.00kg) = 8.24 m/s. for momentum i did p = (3.50kg)(10.00m/s)

4. Mar 28, 2016

### andrewkirk

You don't appear to have used the angles at all. You need to use them to get the correct answer.

Split each momentum vector into two components, one parallel to the direction of motion of the first ball (call that the $x$ direction) and the other perpendicular to it, but in the same plane as all momentum vectors before and after the collision (call that the $y$ direction).

Let $u$ and $v$ be the speeds of the large and small balls after the collision. Then write equations that specify conservation of momentum in the $x$ and $y$ directions. You will have two equations, and two unknowns, so you can solve.

5. Mar 28, 2016

### j doe

i'm still really confused on which two equations to use. could you please tell me and i'll try to solve it out from there?

6. Mar 28, 2016

### Ray Vickson

Are you really having to invent this material all by yourself? Your textbook has no examples like it? Your course notes do not do anything like it?

7. Mar 28, 2016

### j doe

nope

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