Week

Universal Law of Gravitation

Objective

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

Cornell Notes (1/3)Law of Universal Gravitation: Every mass attracts every other mass through a force called gravity

Force (N) =

Gravitational Constant = 6.67 x 10-11

Questions1) Do all things have

their own gravity?

Cornell Notes (2/3)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.

4) What happens to the force when you double the distance?

Cornell Notes (1/5)

Example: Gravitational ForceMr. Fantastic (82 kg) and Dr. Doom (102 kg), are standing 10 meters apart. Calculate the gravitational force between them.

Cornell Notes (2/5)Given:

m1 = 82 kg

m2 = 102 kgr = 10 m G = 6.673 x 10-11 N∙m2/kg2

Unknown:

Fg = ?

Steps1) Define

Mr. Fantastic (82 kg) and Dr. Doom (102 kg), are standing 10 meters apart. Calculate the gravitational force between them.

Cornell Notes (3/5)Choose an equation or situation:

Rearrange the equation to isolate the unknown:

2) Plan

F⃗g=Gm1m2r2

F⃗g=Gm1m2r2

Cornell Notes (4/5)Substitute the values into the equation and solve

3) Calculate

F⃗g=Gm1m2r2

F⃗g=6.67×10−11 ∙

(82)(102)102

F⃗g=5.578788×10− 9

F⃗g=5.579×10− 9N

Cornell Notes (5/5)

So, Mr. Fantastic pulls on Dr. Doom and Dr. Doom pulls on Mr. Fantastic with 5.579 x 10-

9 N.

4) Evaluate