Re: centrifugal force

[Leigh Palmer <palmer@sfu.ca>]

> Am I correct in saying that in the non-inertial frame the "agent"
> which accounts for the accelerations observed ALWAYS has the
> property that the force required is proportional to the mass
> being accelerated?

That is the case indeed. Such forces (of which gravity and the two
inertial forces we've discussed here are the most familiar examples)
act "mysteriously", without any contact with the mass. We call other
forces "forces of contact", but the effects are the same; both kinds
of forces can produce accelerations.

Why do you say the agent has that property? Does the property have
to pertain to the agent? How does one make that decision? Isn't it
more natural to ascribe that property to the force itself? That is
what is usually done, as it is in the statement of the principle
of equivalence in terms of forces. Alternatively it is a property
of the mass itself, the principle of equivalence being stated in
that case by saying that gravitational and inertial masses are
equal.

Leigh