Collusions Without Spin
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Let u=initial vel, v=final vel., 1 denote first object, 2 denote 2nd object.
First transform the coordinates so that u2=0, and v2y=0. That is the second object is at rest and first object puts a force in the x-direction. Ignore the y velocitis (substract it for each objects before calculation, add after calculation).

Remember:
Vel. of seperation = e * Vel. of approach,
where e=coefficient of restitution. For perfectly elastic, e=1. For perfectly inelastic, e=0. e is >=0 and <=1 (with some exceptions like explosions).
(Can show e=1 for elastic collusions by dividine
	m1u1^2-m1v1^2=m2v2^2-m2u2^2 [energy conservation]
by	m1u1  -m1v1  =m2v2  -m2u2   [momemtum conservation])

We have then
m1u1=m1v1+m2v2 [conservation of momentum]
e*u1=v2-v1 [by definition of e]

Therefore, by solving the above 2 eqns,
v1 = (m1-e*m2)*u1/(m1+m2)
v2 = m1*u1*(1+e)/(m1+m2)
