Re: Data types in physics

On Apr 14, 5:35 pm, hel...@xxxxxxxxxxxxxxxxxxxxxxxx (Phillip Helbig---
remove CLOTHES to reply) wrote:

In other words, the quantity of interest (F in the examples above) is
proportional to various things we can measure (like r, or m).  In
general, to make the proportionality an equality, we need a constant.

Do I understand correctly that you are saying that F itself is not a
measurable quantity? We measure other quantities such as r (radius of
orbit) and m (mass of satellite) and then infer the value of F. I am
not sure we can measure these quantities observationally to obtain
force. Force and radius are never together in formulas used to compute
orbits because force is written down temporarily and always cancels.
The same is true for m since that too cancels out of the formulas to
compute orbits. We can only calculate force from given values not from
observations. If r is given then, from F=GM/r2 we can compute F. But
since that computed value of F refers to force in F=ma and since m
cancels, our calculation amounts to computing acceleration. We then
call acceleration force. This suggests to me that orbits are
independent of force.

.

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