Re: Effect of Moon on balance?

["John S. Denker" <jsd@MONMOUTH.COM>]

Recall that the original question was:

> Occasionally some clever students ask me if the gravitational pull
> of the Moon should be included in free-body diagrams. The newspaper
> article implies that it could be done.

I stand by my assertion that it can be done and
is routinely done by gravimeters.

OTOH John Clement makes a good point about
equal-arm balances.  Note that the Subject: line
speaks about balances.

So it appears that two issues are getting tangled up.
 -- The moon does _not_ affect the mass as measured
by a high-precision balance.
 -- The moon _does_ affect the weight as measured
by a high-precision scale.  This must be included
in the free-body diagram at some sufficiently-high
level of precision.