1. One of the most significant intellectual achievements in the history of thought.

2. Every object attracts every other object. Every object attracts every other object. The force between two objects is proportional to their masses and inversely proportional to the square of the distance between their centers. The force between two objects is proportional to their masses and inversely proportional to the square of the distance between their centers. The force acts along the line joining the two objects. The force acts along the line joining the two objects. r

3. One of the most significant intellectual achievements in the history of thought. Every object attracts every other object. Every object attracts every other object. The force between two objects is proportional to their masses and inversely proportional to the square of the distance between their centers. The force between two objects is proportional to their masses and inversely proportional to the square of the distance between their centers. The force acts along the line joining the two objects. The force acts along the line joining the two objects. r

4. One of the most significant intellectual achievements in the history of thought. Every object attracts every other object. Every object attracts every other object. The force between two objects is proportional to their masses and inversely proportional to the square of the distance between their centers. The force between two objects is proportional to their masses and inversely proportional to the square of the distance between their centers. The force acts along the line joining the two objects. The force acts along the line joining the two objects. G = 6.67x10 -11 Nm 2 / kg 2 “Universal gravitational constant”

5. One of the most significant intellectual achievements in the history of thought. Every object attracts every other object. Every object attracts every other object. The force between two objects is proportional to their masses and inversely proportional to the square of the distance between their centers. The force between two objects is proportional to their masses and inversely proportional to the square of the distance between their centers. The force acts along the line joining the two objects. The force acts along the line joining the two objects. G = 6.67x10 -11 Nm 2 / kg 2 “Universal gravitational constant” VERY VERY SMALL! SAME EVERYWHERE!

6. r E – Earth’s radius m E – Earth’s mass. How does universal gravitation relate to the force of gravity on Earth?

7. r E – Earth’s radius m E – Earth’s mass. How does universal gravitation relate to the force of gravity on Earth? This force is commonly called weight W = mg. Now we can see that the gravitational acceleration g is a consequence of the gravitational force.

8. 1) Two satellites of equal mass orbit earth. Satellite A is 2 times farther from the center of earth than Satellite B. How does the gravitational force from the Earth on Satellite A compare to that on Satellite B?

10. 2) A 90 kg satellite orbits the earth at a distance of 300 km. The mass of the earth is 6.0 X 10 24 kg and the radius of the earth is approximately 6.4 X 10 6 m. What is the gravitational force between the satellite and the earth?

11. 1) Two satellites of orbit earth. Satellite A has twice as much mass as Satellite B but has ½ the orbital distance. How does the gravitational force from the Earth on Satellite A compare to that on Satellite B? 2) Calculate the force of gravity between Earth (mass = 6.0 x 10 24 kg) and the moon (mass = 7.4 x 10 22 kg). The average Earth—moon distance is 3.8 x 10 8 m.