1. Describe the universal gravitational law. 2. Evaluate the techniques and models used by Ptolemy and Copernicus to explain the setup of the universe.

3. A child picks up a tennis ball tied to the end of a rope. He swings the rope around, over his head, in a circle. Once the ball is spinning, he lets go of the string and the ball goes flying. Explain which of the following images correctly shows which way the ball will fly and why.

Two images of figures throwing a ball and their potential trajectory