Re: A weighty subject

[John Mallinckrodt <ajmallinckro@CSUPOMONA.EDU>]

On Fri, 15 Oct 1999, Joel Rauber wrote:

> I'm convinced to ignore things like buoyancy in the definition.  But in the
> elevator accelerating upwards, in the frame of reference of the elevator,
> there is an inertial force upwards as well as a normal force upwards on the
> object being weighed on the scale.

No. From the Newtonian viewpoint, there is an inertial force downwards
that adds to the gravitational force making the normal force larger.

> Do you really want to call that inertial force a part of the
> gravitational force.

With the correction above, yes, I do.  But for my introductory students
no.  I would stop at saying that the object's weight is equal to the
magnitude of the normal force, e.g., m(g+a).

John Mallinckrodt      mailto:ajm@csupomona.edu
Cal Poly Pomona          http://www.csupomona.edu/~ajm