# Glancing Elastic Collison

How does n=0 satisfy:

$v_{f1}^2 + nv_{f2}^2 = v_{f1}^2 + v_{f2}^2$?

If n is very small it does not begin to satisfy the relationship. I think n=1 is the only solution.

By the way, billiards players know that the angle between the cue ball and object ball is 90° (absent spin on the cue ball).

AM

that's not the equation I got. My solution looks like

$v_{f1}^2 + nv_{f2}^2 = v_{f1}^2 + n^2v_{f2}^2$

Andrew Mason
Homework Helper
that's not the equation I got. My solution looks like

$v_{f1}^2 + nv_{f2}^2 = v_{f1}^2 + n^2v_{f2}^2$
Ok. Same thing. There is really a discontinuity at n=0. For any n in an arbitrarily small neighbourhood of 0, n does not come close to satisfying the equation.

The condition that the bodies recoil at 90° to each other is not met using classical mechanics if the mass of the second particle (the one initially at rest) is zero.

AM

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