Err, I suppose if you've only had high school physics you'd still look at acceleration that way, but the fact is, an entity's acceleration is determine entirely by the entities own mass and momentum in reaction to other entities. Relative to any mass, every other mass will accelerate toward that mass depending on it's own mass, not the mass of the body it is accelerating toward.bahman wrote: ↑Tue Dec 21, 2021 7:50 pmIn the case of change in position, the first law of Newton, the object keeps its speed and move with constant speed if it is not forced. This is however just happens in abstraction when there is one object in the whole empty universe. Regardless, you can always choose a framework that the object is static within that framework. In the case of acceleration, however, this is always due to the interaction of objects with other objects. Therefore, P2 is correct.RCSaunders wrote: ↑Tue Dec 21, 2021 5:37 pm"P2," is wrong. Aristotle made the same mistake. Neither understood momentum.
Everything that moves only moves itself and will continue to move unless something prevents it. In actuality, all change (change of position: motion, and change in motion: acceleration) is entirely due to the changing entities own nature. All change is the result of an entity reacting to other entities.
Since, "P2," is a false premise, the entire argument if fallacious.
A body in orbit around another stays in orbit because of it's own mass and momentum, not the mass of the body it is orbiting. If either the mass or momentum of the orbiting body were different, the orbit would be different or not at all.
Remembering that an acceleration is a change motion, either it's velocity or direction, a body in orbit is in constant acceleration, without ever changing it's speed. "P2" is just wrong.