- #1

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## Homework Statement

a) Puck A

b) Puck B

## Homework Equations

No idea

## The Attempt at a Solution

No Idea

------------

Where do I even start?

- Thread starter JJones_86
- Start date

- #1

- 72

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a) Puck A

b) Puck B

No idea

No Idea

------------

Where do I even start?

- #2

G01

Homework Helper

Gold Member

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You have to have SOME thoughts on the problem. What have you tried? What concepts does the problem involve?

- #3

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Well I do have some thoughts...

You have to have SOME thoughts on the problem. What have you tried? What concepts does the problem involve?

I know that it has to do with momentum, and directions.

I really just don't know where to start.. After I find the momentum, where would I go from there?

- #4

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Consider the relationship between the momenta before and after collision ...

- #5

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Will the both have the same momentum?Consider the relationship between the momenta before and after collision ...

- #6

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- #7

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Ok, so how would you figure out what the momentum of the two are after the collision?

- #8

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Both p (momentum) and v (velocity) are vectors so it's a vector equation.

Start with the horizontal momenta, one for A before and one each for A and B after. After must be the same as before (conservation!). You don't know the magnitude of the velocities of A and B after so you'll have to call them Va and Vb (or some such) and find another equation to find their values.

I've got to go now.

- #9

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Ok, so how do you find out the velocity of A & B?

Both p (momentum) and v (velocity) are vectors so it's a vector equation.

Start with the horizontal momenta, one for A before and one each for A and B after. After must be the same as before (conservation!). You don't know the magnitude of the velocities of A and B after so you'll have to call them Va and Vb (or some such) and find another equation to find their values.

I've got to go now.

So far I've come up with these equations:

P=m*v

= 0.226kg * 5.59m/s

= 1.263314 kg*m/s

Vay = Va sin 37 -- for A's Y direction

Vax = Va cos 65 -- for A's X direction

Vbx = Vb cos 37 -- for B's X direction

Vby = Vb sin 65 -- For B's Y Direction

So Va = Sqrt((Vax)^2+(Vay)^2)

Just lost on how to find the velocity of Va and Vb...

- #10

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I'm not 100% sure but I think Ma*Va+Mb*Vb=Ma*5.59

- #11

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That just tells me the Vb is 0...I'm not 100% sure but I think Ma*Va+Mb*Vb=Ma*5.59

- #12

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Correct.P=m*v

= 0.226kg * 5.59m/s

= 1.263314 kg*m/s

Also correct. The suffixes a, b, x and y are a smart move. Helpful to use something like 1 for before the collision and 2 for after.Vay = Va sin 37 -- for A's Y direction

Vax = Va cos 65 -- for A's X direction

Vbx = Vb cos 37 -- for B's X direction

Vby = Vb sin 65 -- For B's Y Direction

Correct but not useful in this problem.So Va = Sqrt((Vax)^2+(Vay)^2)

Let M stand for the mass of A, 0.226 kg. How many M is the mass of B?

Slightly modifying what you wrote above, the total momentum in the x direction before the collision can be written

P1x = (V1ax * m1) + (V1bx * mb)

= (5.59 * M) + (0 * 2M)

= 5.59M

Use your expressions for velocities after the collision (V2ax etc.) in an expression for the total momentum in the x direction after the collision:

P2x = ...

What is the total momentum in the y direction before and after the collision?

P1y = ...

P2y = ...

- #13

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That's only correct if the + sign indicates vector addition.I'm not 100% sure but I think Ma*Va+Mb*Vb=Ma*5.59

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