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Re: Derivatives



Dave,

Everything takes time. It is very hard to immagine anything that can
change instantly (dt=0). Even things that we may assume to be instant
for ease of calculation do in fact take some time.

Pete

On Tue, 28 Oct 1997, David Abineri wrote:

I have always pointed out in my Physics classes that a Displacement vs
Time graph must always be differentiable if it is to represent a "real"
situation since one cannot change instantaneously from one velocity to
another.

Today, the question of the differentiability of the Velocity vs Time
graph came into question. It seems to me that this may be non
differentiable, that is to say that acceleration may instantaneously
change from one value to another. HOWEVER, it is difficult for my high
school students to come to grips with this at the intuitive level. I
have shown such graphs to them BUT they seem to be applying their
knowledge of velocity to acceleration incorrectly. I have also said that
an object released from rest suddenly goes from zero acceleration to
9.8m/s/s but I am not sure I have convinced them yet.

Does anyone know of some nice way(s) of getting this point across?

Thanks for any help on this one.

David Abineri


--
David Abineri dabineri@dot-net.net