[Phys-L] Re: A problem of motion and derivatives

[Cherie Lehman <CBLehman@AOL.COM>]

John, I can't think of examples of discontinuous forces aside from
situations where force is exerted as a series of pulses -- for instance force  exerted
by a jackhammer or by antilock brakes. However, each individual pulse  would
be continuous.


In a message dated 11/4/2005 5:54:49 P.M. US Eastern Standard Time,
ajm@CSUPOMONA.EDU writes:

> For  an object with v=0 and a=0 at t < 0, the imposition of a constant  force
> or acceleration at t=0 is a discontinuous event. (This includes  dropping an
> object, where the holding force has to go to zero  instanteously.)

I think it might be the case that the force on a  particle (or the net
force on a system of particles--i.e., an "object")  rarely if ever
really changes discontinuously.  I can't think of  one.  Can anyone
else?

--
John "Slo"  Mallinckrodt

Professor of Physics, Cal Poly  Pomona
<http://www.csupomona.edu/~ajm>

and

Lead  Guitarist, Out-Laws of  Physics
<http://www.csupomona.edu/~hsleff/OoPs.html>
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