Re: Newton's Gravity

Luigi Fortunati <fortunati.luigi@gmail.com> wrote
in <vlejo4$15i8k$1@dont-email.me>:
[...]
# But then, why do two extraordinarily different systems like the Earth's
# mass (6*10^24kg) generate the force of 90kg-weight on my body (mass
# 90kg) and my body generates the *same* opposing force of -90kg-weight
# on the Earth?

Asking "why" in physics usually means "is there a more elementary
explanantion?"

Do you accept

    F = G*m1*m2/r^2     (1)

as an empirical observation?

Indeed, nobody has ever measured the effect of your body's gravitational
force on the Earth. The orders of magnitude for the respective
accelerations are too different. Verification of that formula is only
technically feasible for large pairs of masses, say Earth/Moon or
Sun/Jupiter by observing both bodies in orbit around their barycenter.
This requires each body being subject to equal but opposite forces.

The answer could be "because the masses in (1) appear without preference
for either." Or "because multiplication is commutative". Or "because
when (1) is written in vector notation, the force vectors have the same
magnitude, but opposing direction when the masses are exchanged."

Regards,

Jens
--
Jens Schweikhardt https://www.schweikhardt.net/
SIGSIG -- signature too long (core dumped)