8/8/2019 Behavior of Gases and Flui

1/20

BEHAVIOR

OF GASES

8/8/2019 Behavior of Gases and Flui

2/20

PRESSURE

The amount offorce exerted

per unit area

8/8/2019 Behavior of Gases and Flui

3/20

A

F

P!

Pressure = force / area

8/8/2019 Behavior of Gases and Flui

4/20

A

FP!

Unit on pressure is PASCAL (Pa)

PASCAL = Newton / meter2

8/8/2019 Behavior of Gases and Flui

5/20

The atmosphere on Earth

exerts pressure oneverything.

How much pressure?

About 100,000P

a!!!(~100kPa)

8/8/2019 Behavior of Gases and Flui

6/20

This means that in every square

meter, 100,000N of pressure is

exerted.

100,000N = weight of a large truck

8/8/2019 Behavior of Gases and Flui

7/20

As you move farther from the earth,

the pressure becomes MUCH less.

Which

layer wouldhave the

least

pressure?Why?

8/8/2019 Behavior of Gases and Flui

8/20

Pressure dependson how often the

particles hit the

surfaceMore times = more pressure

8/8/2019 Behavior of Gases and Flui

9/20

Characteristics of Gases

Negligible Volume (verycompressible)

Gases are in constant motion Collisions are completely elastic

No forces off attraction or repulsion

Kinetic energy of a gas is directlyproportional to the temperature

8/8/2019 Behavior of Gases and Flui

10/20

BOYLES LAWFor a given amount of gas

at a constant temperature

the volume of the gasvaries inversely with

pressure.

8/8/2019 Behavior of Gases and Flui

11/20

CHARLESS LAW

Volume of a gasincreases if the

temperature increases(pressure staying constant)

8/8/2019 Behavior of Gases and Flui

12/20

How could Charless

Law be used to

explain why hot airballoons fill up.

8/8/2019 Behavior of Gases and Flui

13/20

If temperature is constant

when

V decreasesthen

P _________INCREASES

8/8/2019 Behavior of Gases and Flui

14/20

If pressure is constant

when

T increasesthen

V _________INCREASES

8/8/2019 Behavior of Gases and Flui

15/20

What happens

when you relax in

a swimming pool?

You float!!!Duhbut why?

8/8/2019 Behavior of Gases and Flui

16/20

BUOYANCY

The ability of a liquidor gas to push up on

an object placed in it

(you in a swimming pool)

8/8/2019 Behavior of Gases and Flui

17/20

If the buoyant forceis greater than the

weight, then object

FLOATS!If notit sinks.

8/8/2019 Behavior of Gases and Flui

18/20

DENSITY

The relationship of themass (weight) to how

much space it takes up

(volume)

8/8/2019 Behavior of Gases and Flui

19/20

v

m

D!

volume

massDensity !

8/8/2019 Behavior of Gases and Flui

20/20

ARCHIMEDES

PRINCIPLE

The buoyant force onan object in a fluid is

equal the weight of the

fluid displaced