1. 14 gases, pressure, Boyle’s Law & Bernoulli’s Principle
RQ: 4, 13, 15, 17, 20.
Exercises: 7, 56.
Problems: 1, 2.

2. Gases independent molecular motion expand “fluid”
exert “isotropic” pressure

3. Archimedes’ Principle for Air
Air provides a small buoyancy, noticeable when object has very low density
Examples: helium or hot-air balloon.
Temperature
Density (kg/m3)
0°C (32°F)
10°C (50°F)
20°C (68°F)
30°C (86°F)

4. Boyle’s Law
for a confined gas, (pressure)x(volume) = constant, i.e., PV = constant.
Ex. A balloon squeezed to half its original size has ...
Reasoning: in a smaller container, the molecules will hit the walls _____________ exerting ____________ on them.

5. Bernoulli’s Principle
When the speed of a fluid* _______ internal pressure in the fluid* ________
*or gas

6. Why does speed decrease pressure?
before the air blows, air molecules exert isotropic pressure, moving in all directions.
air-flow _________________________ giving a preferred direction for air molecules at top of tube. The air molecules below are able to move up….

7. Examples: Roof, Ball

8. Bernoulli’s Principle: Curve Ball

9. Bernoulli’s Principle: Currents

10. summary
gases exert isotropic pressure, but loose this effect when flowing (Bernoulli).
gases exert a small buoyant force on all objects
confined gases have constant product of pressure and volume