1. 2-2-2 Universal Gravitation
Newton’s 4th Law
Universal Gravitation

2. What is Gravity? Attractive force between two objects with mass
Strength of attraction depends on:
Mass of each object (in kilograms)
Distance between the objects (in meters)
Gravitational Constant (G = 6.67 x N∙m2/kg2)

3. Example #1
3000 m
6 x 105 kg
4 x 105 kg
Fg = 1.78 x 10-6 N

4. Gravitational Proportions
The force of gravity is DIRECTLY proportional to mass.
What is the effect on a gravitational system if:
one mass is doubled
Base Case

5. Gravitational Proportions
The force of gravity is DIRECTLY proportional to mass.
What is the effect on a gravitational system if:
both masses are doubled

6. Gravitational Proportions
The force of gravity is DIRECTLY proportional to mass.
What is the effect on a gravitational system if:
one mass is reduced by 1/3

7. Gravitational Proportions
The force of gravity is INVERSELY proportional to the square of distance.
What is the effect on a gravitational system if:
the distance between masses is doubled

8. Gravitational Proportions
The force of gravity is INVERSELY proportional to the square of distance.
What is the effect on a gravitational system if:
the distance between masses is tripled

9. Gravitational Proportions
The force of gravity is INVERSELY proportional to the square of distance.
What is the effect on a gravitational system if:
the distance between masses is halved

10. Gravitational Fields Objects with MASS produce gravitational fields
Field lines point inward from ALL DIRECTIONS

11. End of PRACTICE