#85 Vectors Vanishing and Appearing

[Taylor Brockman]

Sometimes an acceleration vector pops up + then disappears

Sometimes velocity vectors that aren't supposed to be
there momentarily appear. Sometimes vel vectors that
are supposed to be there diappear of flip 180 degrees.

Sweeney note: Think it's a divide by zero issue. Worked
on it some last fall. Underlying representation isn't
quite good enough.