1. Law of Universal Gravitation Law of Universal Gravitation: gravity is a force of attraction that exists between any two objects that have mass. Force of attraction increases when the mass of the objects increases. Force of gravity increases when the objects get closer together.

2. Video Clip http://videos.howstuffworks.com/hsw/9936-exploring-gravity-isaac-newton- and-the-law-of-gravity-video.htmhttp://videos.howstuffworks.com/hsw/9936-exploring-gravity-isaac-newton- and-the-law-of-gravity-video.htm

3. Law of Universal Gravitation The Law of Universal Gravitation The force of attraction between two objects is directly related to the mass of the objects and indirectly related to the distance between them

4. Calculating the gravitation force between objects Equation of Universal Gravitation F: Force (N) G: gravitation constant (6.67 x 10 -11 N-m 2 /kg 2 ) m 1 : mass 1 (kg) m 2 : mass 2 (kg) r: distance between mass 1 and mass 2 (m)

5. Example The mass of Jupiter’s moon, Io, is 8.9 x 10 22 kg. The radius of Io is 1,815 kilometers. Use the equation of universal gravitation to calculate your weight if you were on the surface of Io and had a mass of 50 kg.