Re: [Phys-l] g...

["John Clement" <clement@hal-pc.org>]

According to:
http://curious.astro.cornell.edu/question.php?number=310

Taking into account both of the above effects, the gravitational
acceleration is 9.78 m/s2 at the equator and 9.83 m/s2 at the poles, so you
weigh about 0.5% more at the poles than at the equator.

Now what is meant by conform?  I would assume that you would tell students
that "they have to use 9.81 even though this is not strictly true".  I would
be tempted to say that this what the NYS Regents voted on as the official
value, and that they probably did not bother to measure it.  It might
actually be that value in parts of NYS, but probably not in Houston.  Should
we have a Southern value and a Northern value?  Should we have one for each
state?  Hmmmmmmm.  Do the blue states have different values from the red
ones?  Yes, I do know that Regents exams are regraded by the central office,
or at least they used to be.

BTW one source claimed a value of 9.87 (where???) which would not even round
to 9.8.  I let students measure it and they find it is about 10, which is
the value we then proceed to use.

John M. Clement
Houston, TX


> > On Sun, 19 Nov 2006 08:13:29 -0500 "R. McDermott" <rmcder@gmail.com>
> > writes:
> > > I introduce g as the strength of a  gravitational field due to the
> > Earth, remind them that it varies
> > > with  distance, etc, and has a value of 9.81 N/kg at the Earth's
> > surface.
> >
> > If you wrote that g has a value of 9.8 N/kg at the Earth's surface,
> > I would agree. But is it correct to add the additional significant
> > figure  and make it 9.81 here??
>
> NY State syllabus (and reference table) now gives it as 9.81, not 9.8 as
> in
> previous years.  We are obliged to conform.