How and why does gravity work the way it does? Why are smaller objects attracted to larger objects?
user
I think we need to build up to that.  I think we should first describe the motions of bodies in a vacuum, and then we can see how bodies behave when they’re in a larger region, and then we can see how bodies behave near other bodies.
assistant
Why are smaller objects attracted to larger objects?
user
I’d like to answer that in a slightly different way.  I think the gravitational force is one part attraction and two parts just inertia.  It’s sort of hard for me to explain what that means, but I hope you can understand that I’m talking about the force that pushes a smaller object to move towards the center of a larger one.
assistant
How and why does gravity work the way it does? Why are smaller objects attracted to larger objects?
user
I think we need to build up to that.  I think we should first describe the motions of bodies in a vacuum, and then we can see how bodies behave when they’re in a larger region, and then we can see how bodies behave near other bodies.
assistant
Why are smaller objects attracted to larger objects?
user
It’s due to the gravitational force.  Here’s a picture of a grid that has bodies in it.  It’s a cross-section of a cuboid, so there’s one square that has a red ball, and a few other squares that don’t.  This is a useful set-up because it lets us use vectors.  When you have two vectors, they can be added by lining them up end-to-end.  We can use a little arrowhead to show that the direction is towards the green ball, even though there’s nothing on the screen.  So we say that
assistant
How and why does gravity work the way it does? Why are smaller objects attracted to larger objects?