-----Original Message-----
From: Ludwik Kowalski <KowalskiL@MAIL.MONTCLAIR.EDU>
Why do they often say "plus to
the right and minus to the left" (which is wrong)?
Obviously from the Cartesian coordinate system. Also, up is positive, down
is negative. This causes problems when you want to define down as the
positive direction in Kinematics problems where such a choice eliminates a
slew of minus signs.