Chapter 14: Gases

Question 1

Gas

Answer 1

No definite shape or volume

Question 2

The atmosphere

Answer 2

1) Ocean of air/gases
2) Exerts pressure
3) Competing factors
4) Without the sun, molecules fall to Earth (Earth’s gravity wins)
5) WIthout the Earth’s gravity, molecules fly into space (“Sun wins”)

Question 3

Competing factors

Answer 3

1) Kinetic energy of molecules (Energized by sunlight)
2) Gravity (Pulled down by Earth)

Question 4

Lived at the bottom of an ocean of air (gases)

Answer 4

1) p(liquid) = nearly constant
2) p(atmosphere) = varies a lot

Question 5

Air becomes less dense with

Answer 5

Increasing altitudes (30 km thick atmosphere)

Question 6

Air is more compressed/dense at sea level than at

Answer 6

Higher altitude

Question 7

Liquid (less pressure)

Answer 7

Bottom layer experiences more pressure than the upper layer

Question 8

Liquid (more pressure)

Answer 8

Each layer holds the weight of the previous layers

Question 9

Atmosphere is divided into 5 layers

Answer 9

1) Pressure = Less = Exosphere
2) Pressure = Less = Thermosphere
3) Pressure = Less = Mesosphere
4) Pressure = Less = Stratosphere
5) Pressure = High = Troposphere

Question 10

Air pressure, like water, acts equally in

Answer 10

All directions at a specified height

Question 11

Just as water pressure is caused by

Answer 11

The weight of water

Question 12

Atmospheric pressure is caused by

Answer 12

The weight of air

Question 13

Air is being pulled down by

Answer 13

The gravitational force

Question 14

Atmosphere pressure varies from

Answer 14

One locality to another

Question 15

Atmosphere pressure surrounded by

Answer 15

Air in all directions

Question 16

Pressure decreases with

Answer 16

Increasing altitude

Question 17

The barometer is a device to

Answer 17

Measure atmospheric pressure

Question 18

Pressure consists of a mercury tube

Answer 18

Upside down in a dish filled mercury

Question 19

Pressure the height of the mercury column tells us

Answer 19

The atmospheric pressure

Question 20

Mercury column exerts pressure on

Answer 20

The mercury in the dish

Question 21

Atmosphere exerts pressure on

Answer 21

The mercury in the dish

Question 22

These two pressures must be equal so that

Answer 22

The atmospheric pressure supports the mercury column

Question 23

The pressure and volume of a gas enclosed in a space are

Answer 23

Inversely proportional

Question 24

Piston

Answer 24

A disk or short cylinder that moves up or down against a liquid or gas

Question 25

If you increase pressure, the volume will

Answer 25

Decrease by the same factor

Question 26

Boyle's Law

Answer 26

The pressure and volume of a gas enclosed in a space are inversely proportional

Question 27

The product of pressure and volume of a given mass of gas will always

Answer 27

Remain the same

Question 28

Buoyancy of Air

Answer 28

Archimedes's principle applies to air as well as liquids

Question 29

An object surrounded by

Answer 29

Air is buoyed up by a force equal to the weight of the air displaced

Question 30

Rule for "Lighter than air" objects

Answer 30

1) When the weight of air displaced by an object is greater than the weight of the object, it rises 2) When the weight of air displaced by an object equals the weight of the object, it hovers in air 3) When the weight of air displaced by an object is less than the weight of the object, it is supported by air

Question 31

1) When the weight of air displaced by an object is greater than the weight of the object, it rises

Answer 31

W(ob) < W(disp)

Question 32

2) When the weight of air displaced by an object equals the weight of the object, it hovers in air

Answer 32

W(ob) = W(disp)

Question 33

3) When the weight of air displaced by an object is less than the weight of the object, it is supported by air

Answer 33

W(ob) > W(disp)

Question 34

Gas filled balloons

Answer 34

Buoyancy with hydrogen, the lightest gas (flammable seldom used) and next best buoyancy with helium

Question 35

As balloons rise, atmosphere becomes

Answer 35

Less dense since pressure decreases, volume increases then the balloon expands

Question 36

Gas-filled balloon will continue to rise until the weight of displaced air equals

Answer 36

The total weight of the balloon

Question 37

The buoyant force on the balloon equals

Answer 37

Its weight which says the same thing

Question 38

Bernoulli's Principle

Answer 38

Where the speed of a fluid increases, internal pressure in the fluid decreases (and vice versa)

Question 39

Bernoulli's Principle applies to a smooth, steady flow

Answer 39

1) Mainly applied to incompressible fluids 2) Fluid with constant density

Question 40

Bernoulli's Principle farther apart

Answer 40

1) Flow speed is less 2) Pressure within the fluid is greater

Question 41

Bernoulli's Principle closer apart

Answer 41

1) Flow speed is greater 2) Pressure within the fluid is less

Question 42

Applications of Bernoulli's Principle

Answer 42

1) Blow on the top surface of a paper and the paper rises 2) Reasons: Pressure of the moving air is less than the atmospheric pressure beneath it

Question 43

Wind blowing above and below an airplane wing produces lift

Answer 43

Reasons: Air velocity is greater over the top of the wing than the bottom. Pressure is greater at the bottom and produces lift

Question 44

Plasma

Answer 44

An electrified gas

Question 45

Atom in a plasma are

Answer 45

Ionized and stripped of one or more electrons, with a corresponding number of tree electrons

Question 46

Sun and other stars contain

Answer 46

Plasma

Question 47

Aurora borealis and the aurora australis are

Answer 47

Glowing plasma in the upper atmosphere

Question 48

Fluorescent lamps and neon signs - When a lamp is turned on, a high voltage between electrodes of the tube causes

Answer 48

Electron to flow

Question 49

Electrons ionize some atoms

Answer 49

Forming plasma

Question 50

Plasma provide a conducting path that

Answer 50

Keeps the current flowing

Question 51

Radiations causes the phosphor coating on the tube's inner surface to glow with

Answer 51

The visible light