Re: [Phys-l] definitions ... purely operational, or not

["LaMontagne, Bob" <RLAMONT@providence.edu>]

A properly calibrated scale used in an accelerating elevator definitely does not read mg (g=9.8). It reads m times the free fall acceleration in the frame of refernce of the elevator. If you do not realize the elevator is accelerating (Einstein) you accept the scale reading as your weight (true or apparent is irrelevant).

Bob at PC

> -----Original Message-----
> From: phys-l-bounces@carnot.physics.buffalo.edu [mailto:phys-l-
> bounces@carnot.physics.buffalo.edu] On Behalf Of John Mallinckrodt
> Sent: Monday, November 08, 2010 4:49 PM
> To: Forum for Physics Educators
> Subject: Re: [Phys-l] definitions ... purely operational, or not
>
> On Nov 8, 2010, at 9:30 AM, Anthony Lapinski wrote:
>
> > True weight is mg, while apparent weight is given by a bathroom
> scale,
>
> These two things are identical.  A properly calibrated, properly used
> bathroom scale measures mg where g is precisely the thing that is
> measured in the lab, i.e., the thing we call "the acceleration due to
> gravity" or "freefall acceleration."
>
> I strongly second Joel's recommendation to read the Bartlett article in
> this month's TPT.
>
> John Mallinckrodt
> Cal Poly Pomona
>
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