Mass is the property of matter on which gravity act upon.
gravity
Gravity is working to pull the falling feather down to the ground.
Yes. Gravity. Air resistance (friction again).
Yes, it does. Another opinion: No it doesn't. The formula for the force of gravity involves masses and distance. There is no gravitational force where there is no mass, like, for example between ideas, or between sounds. I notice that the question offers no guidance as to what "non-matter" is.
No force "acts on the force of gravity". Rather, both gravity and other forces - such as drag - will act on objects.
Think of it this way. No matter where you are in the universe some form of gravity will always act upon you. Depending on how close you are to the sun, the earth, or the moon will determine which one acts upon you.
gravity
Tension and compression are the two forces that act upon a bridge.
It does act upon it. If gravity weren't acting upon the ball, it would float into the air instead of remaining on the alley floor.
Gravity and inertia.
Gravity and atmospheric pressure.
Gravity hold the moon in orbit
Entering upon a property with the intent to commit an unlawful act.
Gravity, Air resistence, friction and the push from the floor/table
Congress can act on any matter which Congress believes is of concern for the nation.
Strictly speaking, all matter is attracted to all other matter, and the effect of gravity depends on whats around you and how close you are to it, but i don't think you can be "shielded" from gravity, gravity seems to act regardless of whats in between.
Gravity is working to pull the falling feather down to the ground.