Scattering of two charged particles

[Dazed&Confused]

Homework Statement

Two identical charged particles, each of mass $m$ and charge $e$, are intitialy far apart. One of the particles is at rest at the origin, and the other approaching it with velocity $v$ along the line $x=b, y=0$ where $b=e^2/2 \pi \epsilon_0 mv^2$. Find the scattering angle in the CM frame, and the directions in which the two particles emerge in the Lab.

It then quotes a relevant section which was on Rutherford Scattering

Homework Equations

The Attempt at a Solution

Calling $x=b, y=0$ a line threw me off. I'm not sure what they mean by that.

 

[TSny]

Calling $x=b, y=0$ a line threw me off. I'm not sure what they mean by that.

I'm not sure either. Maybe they mean that the particle is initially traveling in the x-z plane along a line that is parallel to the z axis at x = b.

 

[Dazed&Confused]

That does make sense, although why introduce a third dimension if the particles are in a plane? Anyway I'll try it with what you say.

 

[TSny]

That does make sense, although why introduce a third dimension if the particles are in a plane?

Good point.

The important thing is that the projectile particle is initially moving along a straight line with impact parameter b. I think that's all you really need to know.