Dear Jose Koshy,
It appeared to me that you are almost satisfied with Newtonian Gravitation from your words...." Newtonian mechanics is based on the certainty of the properties of matter. Based on it, the physical world is real; decidability, computability and predictability are its characteristics. But as a theory, Newtonian mechanics is incomplete. It states that bodies have mass and volume, can remain in motion, have gravity (force) and gravity can cause changes in motion."
And you got some doubts....
"1. But it does not say from where bodies acquire motion,"
........... It is just Gravitational attraction forces between bodies(masses), force creates acceleration. Dynamic Universe Model explains that there is a resultant vector force that acts on all bodies and pulls them into motion. The Universe is in Dynamic Equilibrium.
There is nothing to stop the motion, so all bodies will move to the equilibrium...........
Now for the 2. Why motion and gravity are related"
......................... Due to Gravitational attraction the bodies will tend to come near to each other. Just like positive negative charges attract each other try to come near to each other. So this attraction causes motion...............
I request you to please see Dynamic Universe model for all such questions and many of the fundamental and foundational questions about this model are explained in my essay, in addition, I just elaborated what should be the freedom available to an author when the "real open thinking" is supported and what I got from this Dynamic Universe Model..............Have a look at my essay please.
"A properly deciding, Computing and Predicting new theory's Philosophy"
=snp.gupta