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# Mechanics question help: elastic collision of particles in 2D watch

1. Ok so I think I've got an answer for it.

I was told that 2 particles collided.

Particle A:
mass = 10kg
initial velocity = 500 m/s
final(after collision) velocity = 300m/s
Angle of 35degrees from original path after collision

Particle B
mass = 8kg
no initial velocity is given, I assume it is 0.
we need to workout the final velocity.

However, as this is in 2 dimensions should my answer be 2 values? A value for the velocity of particle B in the Y direction and in the X direction?

Also, to check I am on the right lines, I worked out the 2 velocities for B using the momentum equation, ie P=mv???
2. (Original post by Et Tu, Brute?)
Ok so I think I've got an answer for it.

I was told that 2 particles collided.

Particle A:
mass = 10kg
initial velocity = 500 m/s
final(after collision) velocity = 300m/s
Angle of 35degrees from original path after collision

Particle B
mass = 8kg
no initial velocity is given, I assume it is 0.
we need to workout the final velocity.

However, as this is in 2 dimensions should my answer be 2 values? A value for the velocity of particle B in the Y direction and in the X direction?

Also, to check I am on the right lines, I worked out the 2 velocities for B using the momentum equation, ie P=mv???
I would resolve everything into an x- and y-direction and then combine them to get a vector for your final answer, e.g. a final velocity of V m/s at theta degrees.
3. (Original post by Smack)
I would resolve everything into an x- and y-direction and then combine them to get a vector for your final answer, e.g. a final velocity of V m/s at theta degrees.
OK, so just a quick question.

A video I watched on it stated that the angle B (beta) would be larger than the angle because particle B is displaced more than particle A in the Y (-ve Y for that matter) direction. However the angle I calculated for B is considerable smaller than the angle of particle A after the collision.

Also, in the text book I am using the angle B is smaller and under similar circumstances, A is heavier than B, B is at rest initially etc.

And my isn't equal to
4. (Original post by Et Tu, Brute?)
OK, so just a quick question.

A video I watched on it stated that the angle B (beta) would be larger than the angle because particle B is displaced more than particle A in the Y (-ve Y for that matter) direction. However the angle I calculated for B is considerable smaller than the angle of particle A after the collision.

Also, in the text book I am using the angle B is smaller and under similar circumstances, A is heavier than B, B is at rest initially etc.

And my isn't equal to
It's been almost ten years since I have done collision type stuff so I'm not really sure.

Have you drawn a diagram?
5. (Original post by Smack)
It's been almost ten years since I have done collision type stuff so I'm not really sure.

Have you drawn a diagram?
Yeah. I can upload pics later.

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