AT A GIVEN INSTANT, THE ACCELERATION OF A CERTAIN PARTICLE IS ZERO,
WHAT DOES THIS MEAN?

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Clarification of Question by mocha28-ga on 20 Nov 2005 21:02 PST

The choices they give me are (1) the velocity is constant (2) the
velocity is increasing (3) the velocity is decreasing (4) the velocity
is not changing at that instant

Acceleration denotes a change in velocity (v2-v1/t2-t1) over some
interval. This can be due to a change in it's(i.e. velocity's)
magnitude or in it's direction(or both). Based upon the options that
you have, both (1) and (4) qualify as correct answers, but if you are
not attempting a multiple choice answer, you would mark (4) as the
correct option because when you talk of "an" instance, it is actually
a very small duration(t2-t1=dt), and if velocity doesn't change in
that dt(i.e.dv=0), you have a zero acceleration for "that" instance.
Your option (1) would mean a zero acceleration for "any" instance,
since your velocity never changes, of course that would cover the
instance you are worried about.

Does this answer your question??

Yes, thank you very much!!