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

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

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)

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.

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

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….

Examples: Roof, Ball

Bernoulli’s Principle: Curve Ball

Bernoulli’s Principle: Currents

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