1
				2
													3
4
		5					6
		7
8
									9
10
								11				12
					13
14																15
			16
										17				18
				19

Across 2. Bernoulli principle states that an _____ in the speed of a fluid occurs simultaneously with a decrease in the pressure exerted by the fluid. 6. The thin layer of air closest to the surface of a moving object is called the _____ layer. 7. the act of moving or pushing an object forward. 8. In _____ flow the motion of all the fluid particles move in an unpredictable manner caused by pressure and temperature differences. 9. the resistance that happens when two things rub together—like air against an airplane. 10. Hot-air balloons and blimps can float in the air thanks to _____ , an upward force that the air exerts on them. 11. A wing is shaped and tilted so the air moving over it moves faster than the air moving under it. As air speeds up, its _____ goes down. 14. Bernoulli principle states that an increase in the speed of a fluid occurs simultaneously with a _____ in the pressure exerted by the fluid. 16. the force of gravity. It acts in a downward direction—toward the center of the Earth. 17. Upwardly bent _____ help reduce vortex drag. You can see them on many airliners. 19. lift and drag—both created by movement through air—are absent in the near_____ of space.

Down 1. the study of forces and the resulting motion of objects through the air. 3. the force that propels a flying machine in the direction of motion. Engines produce thrust. 4. Air is “stuff” that you must fly through, and it produces two forces of _____: lift and drag. 5. speeds that are faster than the speed of sound 12. speeds that are slower than the speed of sound 13. In _____ flow the motion of all the fluid particles is very orderly. 14. the force that acts opposite to the direction of motion. Drag is caused by friction and differences in air pressure. 15. wing tip vortices create a form of pressure drag called _____ drag. 18. the force that acts at a right angle to the direction of motion through the air. Lift is created by differences in air pressure.