1. Gravity Defined, Law of Universal Gravitation and Inverse Square Law

2. GRAVITY The force of attraction between any two objects with mass.
A field force (non-contact force; surrounds)
A universal force (Gravity is everywhere)
The weakest of the 4 fundamental forces

3. Universal Law of Gravitation
Gravity depends upon
  --Mass
--Distance between masses
As mass increases, so does the amount of gravity.
As the distance between two objects increases, the amount of gravity decreases.

4. Gravity
Gravity depends upon the mass of the objects and the distance between them
More mass, more gravity d M1 M2
Increase distance, decrease gravity d M1 M2

5. Newton’s Universal Law of Gravitation
Differences in the intensity of gravity can be calculated using Newton’s Universal Law of Gravitation 
G is the gravitational constant
G = × m3 /(kg sec2).
Measure distance from center of object.
F = G m1m2 d2

6. Inverse-Square Law
Changes in the intensity of gravity are caused by changes in the mass or in the distance between masses, and follow the inverse-square law.
Electrical and magnetic fields, light, radiation, sound, gravity, and even spray paint.
Systematic decrease in concentration or intensity due to spreading out.
Intensity = 1 d2
2x further away means 4x less gravity!!
10x closer means 100x more gravity!!