/sci/ - Science & Math

>>10707087
Ok, so we're doing collisions in Physics, pretty basic stuff, but my current prof. confuses me the most.
A mass m1 with velocity u1-> collides with mass m2 at rest in the xy plane. They afterwards have the velocities v1-> and v2->, and conservation laws apply.
I was gonna write the rest of the context, but since it would be egregious without TeX, I think it's more effective I just post the thing in kraut runes and translate the relevant stuff.
>Choose coordinate system so coll. happens in xy plane with:
...
>Now ...
>Using this in (4) gives us
...
>Multiplying with m2/(m1+m2) gives us ... or
(ξ - µu1)^2 + η^2 = (µu1)^2
µ is the reduced mass.

I'm trying to understand how he came to the equation at the end with (µu1)^2, but I can't quite wrap my head around it.
Closest I came was
2ξu1/(m1+m2) = u1^2 - v1^2
but even there I can't progress.
t. brainlet humbly requesting help.