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Across 1. Friction is needed for ________________ . 8. Where do jet planes fly through? 10. It is a condition of the atmosphere at a given time and place. 12. It is the force of air pushing on an area. (2 Words) 13. What is the force of pushing upward in the fluid? 14. What is the most gas in the air? 16. What steers the boat by changing the direction of thrust? 18. Gravity __________the takeoff of the plane. 19. What gives thrust in an airplane? 21. It describes how hot or cold something is. (2 Words) 23. What is the force that holds an object in the air? 25. What is the layer that is closest to the earth? 27. Friction is when two objects ____________ against each other. 29. Lift works against ___________ . 30. What does the shape of the wings help create? 31. What is the force that is opposite to motion?

Down 2. What is the friction between wheels and rails called? 3. Which layer protects the earth from harmful UV rays? (2 Words) 4. What gives the boat thrust to move forward? (3 Words) 5. What produces the harmful UV rays? (2 Words) 6. Which layer is the outermost layer? 7. It is the force that moves an object forward. 9. Where does most of the water vapor come from? (2 Words) 11. What is the force that works against motion? 15. It is the measure of how much moisture in the air or the amount of water vapor in the air. 17. What can slow the motion of the rocket? 20. Air is a mixture of _______________ . 22. What is the Earth's atmosphere made up of? 24. What pulls the rocket toward ground? 26. Thrust can be pushing or _____________ . 28. What do rockets use to overcome gravity?