Universal Law of Gravitation Week

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

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 10-11 N (m/kg)2

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?

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.

Cornell Notes (2/5) Steps Define Given: m1 = 82 kg m2 = 102 kg r = 10 m G = 6.673 x 10-11 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.

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

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) 10 2 F g =5.578788× 10 −9 F g =5.579× 10 −9 N

Cornell Notes (5/5) Evaluate So, Mr. Fantastic pulls on Dr. Doom and Dr. Doom pulls on Mr. Fantastic with 5.579 x 10-9 N.