Question

Why is the law of gravity an example of a universal law? Gravity is the reason the Earth revolves a?

Gravity is a force that affects everyone on Earth.

Gravity is a force that exists between any two masses in the universe.

Gravity is the attraction of any mass to any other mass.

Answer 1

Gravity
It's a force of attraction that exists between any two objects that have mass. The more mass they have, the greater the force of attraction. The closer they are, the greater the force of attraction.
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For most objects you get near every day, the force of attraction is so incredibly small that you would never notice the force. Gravity is a very weak force, so between common objects like you and your pencil, the force of attraction is very small because your mass and the mass of your pencil are small. We only get noticeable amounts of gravity when at least one object is very massive... like a planet. The force of attraction between you and the planet Earth is a noticeable force! We call the force of attraction between you and the Earth, your weight. Weight is another name for the force of gravity pulling down on you or anything else.

G is the universal gravitational constant. It is basically a conversion factor to adjust the number and units so they come out to the correct value. This is a universal constant so it is true everywhere.

m1 is the mass of one of the objects.

m2 is the mass of the other object.

r is the radius of separation between the center of masses of each object.

FG is the force of attraction between the two objects.