1. Universal Law of Gravitation
Week

2. Student will: Objective
Describe and calculate how the magnitude of the gravitational force between two objects

3. Force (N) = G∙mass 1 kg ∙mass 2 (kg) distance (m) 2
Cornell Notes (1/3)
Questions
Do all things have their own gravity?
Law of Universal Gravitation:
Every mass attracts every other mass through a force called gravity
F g = G∙ m 1 ∙ m 2 r 2
Force (N) = G∙mass 1 kg ∙mass 2 (kg) distance (m) 2
Gravitational Constant =
6.67 x N (m/kg)2

4. Cornell Notes (2/3)
What happens to the force when you cut the distance in half?
Cut the distance in half, and the force is 4 time greater. Double the distance, and the force is 1/4th what it was.
What happens to the force when you double the distance?

5. Cornell Notes (1/5)
Example: Gravitational Force Mr. Fantastic (82 kg) and Dr. Doom (102 kg), are standing 10 meters apart. Calculate the gravitational force between them.

6. Cornell Notes (2/5)
Steps
Define
Given:
m1 = 82 kg
m2 = 102 kg
r = 10 m
G = x N∙m2/kg2
Unknown:
Fg = ?
Mr. Fantastic (82 kg) and Dr. Doom (102 kg), are standing 10 meters apart. Calculate the gravitational force between them.

7. Cornell Notes (3/5) F g =G m 1 m 2 r 2 F g =G m 1 m 2 r 2
Plan
Choose an equation or situation:
Rearrange the equation to isolate the unknown:
F g =G m 1 m 2 r 2
F g =G m 1 m 2 r 2

8. Cornell Notes (4/5) F g =G m 1 m 2 r 2
Calculate
Substitute the values into the equation and solve
F g =G m 1 m 2 r 2
F g =6.67× 10 −11 ∙ (82)(102)
F g = × 10 −9
F g =5.579× 10 −9 N

9. Cornell Notes (5/5)
Evaluate
So, Mr. Fantastic pulls on Dr. Doom and Dr. Doom pulls on Mr. Fantastic with x 10-9 N.