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

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".)