Re: [Phys-L] gravity, weightlessness, etc.

[John Denker <jsd@av8n.com>]

On 01/19/2018 05:20 PM, LaMontagne, Bob wrote:

> Is it still considered OK to define your weight as the force on the
> bottom of your shoes when you attempt to stand upright? That seems to
> take into account all the "real" and "apparent" forces involved.
I'd say it's /equal to a good approximation/.
It's a reasonable starting point ... but I
wouldn't promote it to a "definition".

There's a 0.1% correction due to buoyancy in air,
which means the scale-reading is less than the
true weight.

There are larger corrections if you're flailing
your arms as you "attempt" to stand upright ...
although these average out over time.

Also I assume the intent was the downward force
exerted /by/ the bottom of your shoes (not the
upward acting "on" them).
	Weight = F = mg
where g is a vector in the /down/ direction, by
definition.  (This is not the definition of g,
but rather the definition of "down".)