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Beginner's Guide to Propulsion
Gas Properties Definitions
Answers will vary. Suggested answers are shown below:

1. What is the meaning of the term micro? small scale, molecular

2. What is the meaning of the term macro? large scale, whole gas

3. In terms of observation, what is the difference between micro and macro? macro scale is based on things observed and measured; micro is based on theories, not direct observation

4. Although air is treated as a uniform gas, its major component is nitrogen

5. Why doesn't a gas have a fixed shape or size? Because molecules are free to move about, they fill any container, regardless of shape or size.

6. Which theory is used to describe the behavior of gases? kinetic theory of gases

7. What does the theory above assume about the size of gas molecules? The size of the gas molecules is very small compared to the distance between the molecules.

8. What does the theory assume about the motion of gas molecules? The motion of gas molecules is constant and random.

9. A gas is an example of a fluid. What other state of matter is an example of a fluid? Liquids are also fluids.

10. Obtain two beakers and fill them with water. Carefully add a dropper of dye or food coloring to the top of the water. Describe the process you observe: The dye starts to move through the beaker of water, spreading out, becoming more diluted.

11. What is the name of the process you observed? diffusion

12. Forcefully squirt a dropper of dye or food color into the second beaker of water and describe the process you observe. The dye moves in the direction that it was squirted into the water; it flows in that direction, away from the dropper.

13. Why did the dye move differently the second time? A force was added from the dropper.

14. If you now stir the dye around in a circular motion in the beaker, you should see rotational motion.

15. What is viscosity? stickiness

16. What is a boundary layer? a layer of air near a surface which, in effect, changes the shape of an object, such as an airplane wing

17. Which scientist introduced the concept of boundary layer? Ludwig Prandtl

18. This discovery is the greatest discovery in the field of fluid mechanics.

19. Air viscosity and boundary layer are important in flight because they affect which two forces involved in flight? lift and drag

20. At high speeds, the air is compressed during flight. What happens to the density of the air? When air is compressed, its density increases because the same mass of air is pressed into a smaller volume.

Related Pages:
Propulsion Activity Index
Propulsion Index


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Editor: Tom Benson
NASA Official: Tom Benson
Last Updated: Thu, Jun 12 04:39:29 PM EDT 2014

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