Unit 3 Forces and Energy

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Across
  1. 4. A push or a pull that can change an object’s motion.
  2. 7. A force that acts without objects touching, such as gravity.
  3. 8. The force of gravity acting on an object.
  4. 11. The force that attracts objects with mass toward each other.
  5. 12. The unit used to measure force.
  6. 15. An icy object that orbits the Sun and forms a glowing tail when near the Sun.
  7. 18. A large body formed from planetesimals that may eventually become a planet.
  8. 20. A small rocky object that orbits the Sun.
  9. 23. The Sun and all the objects that orbit around it, including planets, moons, asteroids, and comets.
  10. 25. Motion of an object when gravity is the only force acting on it.
  11. 27. process where particles of dust and rock stick together to form larger bodies.
  12. 28. A force that slows objects moving through air.
  13. 30. The planet we live on. It orbits the Sun and has gravity that pulls objects toward its surface.
Down
  1. 1. A shape or path that forms a circle. Many objects in space move in nearly circular orbits around larger objects.
  2. 2. The strength of gravity at a certain place. On Earth it is about 9.8 N/kg.
  3. 3. Forces that cancel each other out so an object does not change motion.
  4. 5. A force that acts when objects touch each other (for example when a table holds up a book).
  5. 6. A young star forming from collapsing gas and dust.
  6. 9. The area around a massive object where another object feels the force of gravity.
  7. 10. Forces that cause an object to start moving, stop moving, or change direction.
  8. 13. A huge cloud of gas and dust in space where stars and planetary systems can form.
  9. 14. A streak of light produced when a small space rock burns up in Earth’s atmosphere.
  10. 16. A piece of rock from space that survives the atmosphere and reaches the ground.
  11. 17. Small early objects that formed from dust and rock and later combined to make planets.
  12. 19. collapse The process where gravity pulls gas and dust together to start forming stars and planets.
  13. 21. A perfectly round three-dimensional shape, like a ball. Planets and stars are approximately spherical because gravity pulls matter equally toward the center.
  14. 22. The path an object follows around another object in space.
  15. 24. The star at the center of our solar system. Its gravity keeps the planets, asteroids, and comets in orbit around it.
  16. 26. A natural satellite that orbits a planet. Earth’s Moon orbits Earth because of gravity.
  17. 29. The amount of matter in an object. Mass is measured in kilograms (kg).