Astronomy Chapter 3 and 4

2. Kepler’s ______ law states that planets orbit in ellipses.
4. According to Kepler’s second law, planets travel _____ when nearer to the sun.
5. The universal law of gravitation is an example of an _____ square law.
10. Newton's second law states that ______ is proportional to the force acting on an object.
12. The amount of matter in an object.
14. Kepler’s ______ law states that more distant planets orbit the sun at a slower average speed.
15. A scientific model must make _______ predictions.
17. Science progresses through the c reation and testing of ______
19. Thermal energy is a special type of ______ energy.
20. A push or a pull.

1. An object has more/less gravitational potential energy when it is higher.
2. Weight depends on mass and the _____ acting upon the object.
3. Speed is distance over _____.
6. The acceloration due to gravity is 9.8 meters per second ______.
7. An educated guess.
8. The first hallmark of science restricts explanations to rely solely on ______ causes.
9. Momentum is mass times _____.
11. The earth needs no fuel to keep to keep it going around the sun. This is due to conservation of _______ momentum.
13. Velocity is _____ and direction.
16. A powerful, yet simple, model that makes predictions and survives repeated and varied testing.
18. _____ cannot be created or destroyed. It can only change form.