| A | B |
|---|
| Geocentric model | Greek model that Earth was center of the Universe (81) |
| Heliocentric model | Copernicu's model that sun was center of the Universe (82) |
| Big Bang Theory | Universe began with big explosion of matter and energy (83) |
| Universe | has been expanding since its beginning according to Big Bang Theory (84) |
| Our Solar System | contains star, comets, asteroids, planets, moons (85) |
| Forces | Causes interaction between bodies (86) |
| The greater the mass | The greater the gravitational force (87) |
| Elliptical orbits | Caused by combination of inertia and gravity of orbiting object (88) |
| Kepler's Law | Theory of Elliptical orbits (88) |
| Newton's 1st Law | objects in motion stay in motion in straight lines and objects at rest stay at rest. (89) |
| Newton's 2nd Law | Force is required to change speed or direction. (90) |
| Newton's 3rd Law | Every action has an equal and opposite reaction. (91) |
