1. Bell Ringer What celestial body is at the center of our solar system? What is celestial body or bodies has the farthest orbit in our solar system? What shape are the planets orbits? Grab a book when you finish the bell ringer questions.

2. PLANETARY MOTION AND GRAVITATION By: Mr. Schlamb

3. Sun Centered or Earth Centered Long believed the Earth was center of solar system Nicholas Copernicus Polish astronomer: Planets and stars don’t agree with Earth-centered model Work published in 1543 while on his deathbed Motion is much more easily understood with Sun at center Tycho Brahe did not agree with this Says Sun and moon orbit Earth All other bodies orbit the Sun

4. Johannes Kepler 3 Laws: The paths of the planets are ellipses with the Sun at one focus An imaginary line form the Sun to a planet weeps out equal areas in equal time intervals This is an equation: First two laws apply to each planet moon and satellite individually The third law related the motion of several objects about a single body: compares planets distance from Sun to their periods about the Sun

5. Newton’s Law of Universal Gravitation Law of Universal Gravitation– objects attract other objects with a force that is proportional to the product of their masses and inversely proportional to the square of the distance between them In short the equation is: The force of attraction between tow objects must be proportional to the objects masses is known as gravitational force

6. What is G? G stands for the universal gravitation constant G= **Note G is a constant its value never changes

7. Period of a Planet Time it takes for a planet to make one full revolution Period of Planet orbiting the Sun:

10. Exit Slip Using Newton’s law of universal gravitation, find the force exerted between two objects separated by a distance of 8m. Object one has a mass of 12kg while object two has a mass of 15kg. What would you like more practice with after today lesson? What is one thing you would like to do more of in class? Is there anything you don’t understand from todays lesson?