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Diving Physics. Sources. Joiner, J.T. (ed.). 2001. NOAA Diving Manual - Diving for Science and Technology, Fourth Edition. Best Publishing Company, Flagstaff, AZ. Reference Materials: In conjunction with this presentation, refer to: NOAA Diving Manual Chapter 2. Objectives.

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sources
Sources
  • Joiner, J.T. (ed.). 2001. NOAA Diving Manual - Diving for Science and Technology, Fourth Edition. Best Publishing Company, Flagstaff, AZ.
  • Reference Materials:
    • In conjunction with this presentation, refer to:
      • NOAA Diving Manual Chapter 2
objectives
Objectives
  • After completing this training module you will be able to:
    • Differentiate among atmospheric, hydrostatic, absolute, gauge, and partial pressures
    • Define density and specific gravity
    • State the differences between freshwater and seawater important to diving
objectives1
Objectives
  • After completing this training module you will be able to:
    • Perform basic calculations involving the units of measurement and temperature commonly used in diving
    • Define Archimedes’ Principle and describe the three states of buoyancy
objectives2
Objectives
  • After completing this training module you will be able to:
    • Differentiate between the gases used in, or associated with, diving
    • State and apply Boyle’s Law, Charles’/Gay-Lussac’s Law, Dalton’s Law, Henry’s Law, and the General Gas Law
objectives3
Objectives
  • After completing this training module you will be able to:
    • Explain how moisture in the breathing gas and humidity impact the diver and the diver’s equipment
    • Explain how the properties of light and sound are affected by diving
general
General
  • Physics is the field of science dealing with matter and energy and their interactions
  • This chapter explores physical laws and principles that pertain to the diving environment and its influence on the diver
general1
General
  • The principles of physics provide the keystone for understanding the reasons for employing various diving procedures
pressure
Pressure
  • Pressure is force acting on a unit area
  • Pressure = force / area
  • P = F/A
  • In the USA pressure is typically measured in pounds per square inch (psi)
  • A diver, at any depth, must be in pressure balance with the forces at that depth
atmospheric pressure
Atmospheric Pressure
  • This is the pressure exerted by the earth’s atmosphere
  • At sea level it is equal to 14.7 psi, or one atmosphere (atm)
  • It decreases with altitude above sea level
    • For example, at 18,000 ft atmospheric pressure is 7.35 psi or half that at sea level
hydrostatic pressure
Hydrostatic Pressure
  • Pressure due to the weight of water is called “hydrostatic pressure”
  • The deeper the dive, the greater the weight of the water, the greater the hydrostatic pressure
  • Hydrostatic pressure affects the diver from all sides equally
hydrostatic pressure1
Hydrostatic Pressure
  • In seawater hydrostatic pressure increases at a rate of 0.445 psi per foot
  • Hydrostatic pressure reaches one atm at 33 ft in seawater, and increases by one atm for every additional 33 ft thereafter
hydrostatic pressure2
Hydrostatic Pressure
  • In freshwater hydrostatic pressure increases by 0.432 psi per foot
  • Hydrostatic pressure reaches one atm at 34 ft in freshwater and increases by one atm for every additional 34 ft thereafter
absolute pressure
Absolute Pressure
  • The sum of atmospheric pressure plus hydrostatic pressure equals “absolute pressure”
absolute pressure1
Absolute Pressure
  • Absolute pressure can be expressed as: “psia” (pounds per square inch absolute), “ata” (atmospheres absolute), “fswa” (feet of seawater absolute), “ffwa” (feet of freshwater absolute), or “mmHga” (millimeters of mercury absolute)
gauge pressure
Gauge Pressure
  • The difference between atmospheric pressure and the pressure being measured is “gauge pressure”
  • It can be expressed as psig (pounds per square inch gauge)
  • The zero reading on a cylinder pressure gauge at sea level is actually equal to 14.7 psia
  • Gauge pressure + 14.7 = ata
partial pressure
Partial Pressure
  • The total pressure of a mixture of gases is equal to the partial pressure of each gas in the mixture
  • For our purposes air is composed of 21% oxygen and 79% nitrogen
  • Thus, the partial pressure at sea level of nitrogen is 0.79 ata, and oxygen is 0.21 ata
density
Density
  • Density can be defined as weight per unit volume
  • Density = Weight / Volume or D = W / V
  • Gas density is related to absolute pressure
  • As depth increases, the density of the breathing gas increases and thus it becomes heavier per unit volume
density1
Density
  • Freshwater has a density of 62.4 pounds per cubic foot
  • Seawater has a density of 64 pounds per cubic foot
  • As a result, freshwater floats on top of seawater and a diver floats more easily in seawater than in freshwater
specific gravity
Specific Gravity
  • Specific gravity is the ratio of the weight of a given volume of a substance to that of an equal volume of another substance
  • The density of a substance divided by the density of the standard for a group of substances equals the specific gravity of the substance
  • Water is the standard for liquids and solids
  • Air is the standard for gases
specific gravity1
Specific Gravity
  • Substances that are more dense than freshwater have a specific gravity greater than 1.0
  • The specific gravity of seawater is 64/62.4 = 1.026
freshwater
Freshwater
  • H2O is odorless, tasteless and very slightly compressible
  • It freezes at 32F, and boils at 212F
  • In its purest form, it is a poor conductor of electricity
seawater
Seawater
  • Seawater contains almost every substance known
  • The most abundant chemical is sodium chloride (common table salt)
  • Seawater is a good conductor of electricity
slide24
pH
  • The pH of an aqueous solution expresses the level of acids or alkalis present
  • The pH of a liquid can range from 0 (strongly acidic) to 14 (strongly alkaline); a pH of 7 is neutral
units of measurement
Units of Measurement
  • There are two systems for specifying force, length and time: English and Metric (also known as the International System of Units or SI)
units of measurement1
Units of Measurement
  • The English System is based on the pound (lb), the foot (ft), and the second (s)
  • The International System is based on the kilogram (kg), the meter (m), and the second (s)
length
Length
  • 1 meter equals 39.37 inches
  • 1 meter equals 3.28 feet (i.e., 39.37 / 12)
  • Covert 10 feet to meters:
    • 10 ft / 3.28 ft = 3.05 m
  • Convert 10 meters to feet:
    • 10 m x 3.28 ft = 32.8 ft
slide28
Area
  • In both the English and SI system, area is expressed as a length squared
  • For example:
    • A room that is 12 feet by 10 feet would have an area of 120 square feet (12 ft x 10 ft)
    • A room that is 3.66 m by 3.05 m would have an area of 11.16 square meters
volume
Volume
  • Volume is expressed in units of length cubed
  • Length x Width x Height = cubic feet (ft3) or cubic meters (m3)
    • The English System, in addition to ft3,uses other units of volume such as gallons
    • The SI uses the liter (L). One liter = 1000 cubic centimeters (cm3) or 0.001 cubic meters (m3), which is one milliliter (mL)
weight
Weight
  • The standard measure of weight in the English System is the pound (lb)
  • The standard measure of weight in the International System of Units is the kilogram (kg)
  • One liter of water at 4C weighs 1 kg or 2.2 lbs
weight1
Weight
  • Convert 180 pounds to kilograms:

180 lbs / 2.2 lbs = 81.8 kg

  • Convert 82 kilograms to pounds:

82 kg x 2.2 lbs = 180.4 lbs

temperature
Temperature
  • Heat is associated with the motion of molecules
  • The more rapidly the molecules move, the higher the temperature
  • Temperature is usually measured either with the Fahrenheit (°F) scale or with the Celsius (centigrade) scale (°C)
temperature1
Temperature
  • Temperature must be converted to absolute when the gas laws are used
  • The absolute temperature scales are Rankine (R) or Kelvin (K), and are based on absolute zero
  • Note the degree symbol (°) is only used with Fahrenheit temperatures
temperature2
Temperature
  • The Fahrenheit (°F) and Rankine (R) temperature scales are used in the English System
  • To convert Fahrenheit to absolute temperature Rankine:

°F + 460 = R

temperature3
Temperature
  • The Celsius (C) and Kelvin (K) temperature scales are used in the International System of Units
  • To convert from Celsius to absolute temperature Kelvin:

°C + 273 = K

buoyancy
Buoyancy
  • Archimedes’ Principle:

“Any object wholly or partly immersed in a fluid is buoyed up by a force equal to the weight of the fluid displaced by the object”

buoyancy1
Buoyancy
  • Buoyancy is termed “Positive” when the weight of the displaced fluid is greater than the submerged object (i.e., object floats)
  • Buoyancy is termed “Negative” when the weight of the displaced fluid is less than the weight of the submerged object (i.e., object sinks)
  • If the weight of the object is equal to the weight of the fluid displaced the buoyancy is “Neutral” (i.e., object is suspended)
buoyancy2
Buoyancy
  • Buoyancy is dependent upon the density of the surrounding liquid – the greater the density the greater the buoyancy force
  • Seawater has a density of 64 pounds per cubic foot
  • Freshwater has a density of 62.4 pounds per cubic foot
gases important for diving
Atmospheric Air

Oxygen (O2)

Nitrogen (N2)

Helium (He)

Carbon Dioxide (CO2)

Carbon Monoxide (CO)

Argon (Ar)

Neon (Ne)

Hydrogen (H2)

Gases Important for Diving
slide40
Air
  • Atmospheric Air is the most common gas breathed underwater
  • It is composed of approximately:

78% Nitrogen

21% Oxygen

1% other gases

oxygen o 2
Oxygen (O2)
  • Oxygen is required for human life
  • However, under certain conditions it can be toxic
  • Oxygen is required for fire
oxygen o 21
Oxygen (O2)
  • O2 comes in 3 basic grades:
    • Aviator’s Oxygen (Grade A) – ultra dry
    • Medical/Industrial Oxygen (Grade B)
    • Technical Oxygen (Grade C) – may contain contaminants - not recommended for diving (but ok for treating decompression sickness if no other O2 available – better than nothing)
nitrogen n 2
Nitrogen (N2)
  • Is the largest proportion of the air we breathe, but plays no part in metabolism
  • Nitrogen plays the major role in decompression
nitrogen n 21
Nitrogen (N2)
  • As the partial pressure of N2 increases with depth, it produces an intoxicated state, nitrogen narcosis (also known as “inert gas narcosis”), that is characterized by loss of judgment and disorientation
helium he
Helium (He)
  • Helium is used extensively in deep diving
  • It does not cause the problems associated with nitrogen narcosis
  • It has a lower density than nitrogen that reduces breathing resistance
  • The disadvantages of He include “Donald Duck” voice and heat loss due to its high thermal conductivity
carbon dioxide co 2
Carbon Dioxide (CO2)
  • CO2 is a natural by-product of metabolism
  • Excess carbon dioxide can cause unconsciousness that can be fatal in divers
carbon dioxide co 21
Carbon Dioxide (CO2)
  • Elevated CO2 levels may further predispose a diver to nitrogen narcosis, oxygen toxicity, and decompression sickness
carbon monoxide co
Carbon Monoxide (CO)
  • CO is a poisonous gas which interferes with the blood’s ability to carry oxygen
carbon monoxide co1
Carbon Monoxide (CO)
  • CO is produced by the incomplete combustion of fuels and is found in the exhaust of internal-combustion engines and overheated oil-lubricated compressors
  • The effects can be lethal
argon ar
Argon (Ar)
  • Argon has narcotic properties and a density which make it inappropriate as a breathing gas
  • It is frequently used to inflate dry suits because its higher density reduces conduction of heat
neon ne
Neon (Ne)
  • Neon causes less voice distortion than helium and has lower thermal conductivity
  • However, it is expensive and causes increased breathing resistance under work load
hydrogen h 2
Hydrogen (H2)
  • Hydrogen is readily available and produces less breathing resistance at depth than other gases
  • Its major disadvantage is that is explosive
gas laws
Gas Laws
  • Gases are subject to three interrelated factors: pressure, volume, and temperature
  • A change in one factor results in a measurable change in the others
  • This change is true with pure gases or a gas mixture
  • The relationships among these three factors have been defined as the gas laws
boyle s law
Boyle’s Law
  • “For any gas at a constant temperature, the volume of the gas will vary inversely with the pressure”
boyle s law applied
Boyle’s Law Applied:

Credit: Permission granted by Best Publishing Company (NOAA Diving Manual 4th Ed.) Flagstaff, AZ

boyle s law1
Boyle’s Law
  • An open-bottom diving bell containing 24 cubic feet of gas is lowered from the surface to a depth of 33 fsw. No gas is supplied or lost during decent. Calculate the volume of air space in the bell at 33 fsw.

Credit:Permission granted by Best Publishing Company (NOAA Diving Manual 4th Ed.) Flagstaff, AZ

boyle s law2
Boyle’s Law
  • Boyle’s Equation: P1V1=P2V2
    • P1 = initial pressure surface absolute
    • V1 = initial volume in cubic feet (ft3)
    • P2 = final pressure absolute
    • V2 = final volume in cubic feet (ft3)
boyle s law3
Boyle’s Law
  • An open-bottom diving bell containing 24 cubic feet of gas is lowered from the surface to a depth of 33 fsw
    • P1 = Surface or 1 ata
    • V1 = 24 ft3
    • P2 = 33 fsw or 2 ata
    • V2 = Unknown
boyle s law4
Boyle’s Law

P1 V2

___________________________

P2

V2 =

boyle s law5
Boyle’s Law

1 ata x24 ft3

___________________________

2 ata

V2 =

boyle s law6
Boyle’s Law

V2 =

12 ft3

Credit: Permission granted by Best Publishing Company (NOAA Diving Manual 4th Ed.) Flagstaff, AZ

charles gay lussac s law
Charles’/ Gay-Lussac’s Law
  • “For any gas at a constant pressure, the volume of the gas will vary directly with the absolute temperature or for any gas at a constant volume, the pressure of the gas will vary directly with the absolute temperature”
charles law volume change
Charles’ Law - Volume Change
  • Our diving bell also experienced a temperature change from 80F to 45F
  • Compute the volume change
charles law volume change1
Charles’ Law - Volume Change

V1

________

V2

T1

________

T2

=

charles law volume change2
Charles’ Law - Volume Change
  • Charles’ Equation: V1 / V2 = T2 / T2
    • V1 = volume at 33 ft = 12 ft3
    • T1 = 80oF + 460 = 540 Rankine
    • T2 = 45oF + 460 = 505 Rankine
    • V2 = Unknown
charles law volume change3
Charles’ Law - Volume Change

V1 T2

___________________________

T1

V2 =

charles law volume change4
Charles’ Law - Volume Change

12 ft3 x 505 R

__________________________________

540 R

V2 =

charles law volume change6
Charles’ Law - Volume Change
  • The volume in the diving bell was reduced an additional 0.78 ft3 due to the decrease in temperature
gay lussac s law pressure change
Gay-Lussac’s Law – Pressure Change
  • A scuba cylinder contains 3,000 psig (3,014.7 psia) at 64oF. It is left in the sun on a hot summer day. What will the cylinder pressure be if the temperature of the air inside reaches 102oF?
gay lussac s law pressure change1
Gay-Lussac’s Law – Pressure Change

P1

________

P2

T1

________

T2

=

gay lussac s law pressure change2
Gay-Lussac’s Law – Pressure Change
  • P1 = 3,014.7
  • T1 = 64oF + 460 = 524 Rankine
  • T2 = 102oF + 460 = 562 Rankine
  • P2 = Unknown
gay lussac s law pressure change3
Gay-Lussac’s Law – Pressure Change

P1 T2

___________________________

T1

P2 =

gay lussac s law pressure change4
Gay-Lussac’s Law – Pressure Change

3,014.7 x 562 R

_______________________________________

524 R

P2 =

gay lussac s law pressure change6
Gay-Lussac’s Law – Pressure Change
  • To convert to gauge pressure, subtract 14.7

3,233.3 psia – 14.7 psi = 3,218.6 psig

dalton s law
Dalton’s Law
  • “The total pressure exerted by a mixture of gases is equal to the sum of the pressures of each of the different gases making up the mixture, with each gas acting as if it alone was present and occupied the total volume”
dalton s law1
Dalton’s Law
  • Pt = PP1 + PP2 + PP3, etc.
    • Pt = Total Pressure
    • PP1, etc. = Partial pressure of first gas, etc.
  • Partial pressure of a given quantity of a particular gas is the pressure it would exert if it alone occupied the total volume
dalton s law2
Dalton’s Law
  • The figure Px is used to indicate partial pressure. The subscript x represents the specific gas
  • To determine the partial pressure of a gas mixture:

Px = Gas % x Pt

dalton s law3
Dalton’s Law
  • A container is filled with air at a total pressure of 14.7 psi. What is the partial pressure of the nitrogen?
  • For this example air consists of:

N2 = 78.08%

O2 = 20.95%

CO2 = 0.03%

Other gases = 0.94%

dalton s law4
Dalton’s Law

Px = Gas % (decimal) x Pt

PN2 = 0.7808 x 14.7 psi

PN2 = 11.478 psi

dalton s law5
Dalton’s Law

Expressed in atmospheres:

PN2 = 0.7808 x 1.0 atm

PN2 = 0.7808 atm

dalton s law6
Dalton’s Law

What is the partial pressure of nitrogen within a scuba cylinder of air filled to 2,000 psi?

PN2 =

0.7808 x 2,000 psi

PN2 =

1,561.6 psi

dalton s law7
Dalton’s Law

Expressed in atmospheres:

PN2 = 2,000 psi x 1 atm/14.7 psi = 136.05 atm

PN2 = 0.7808 x 136.05 atm

PN2 = 106.23 atm

dalton s law8
Dalton’s Law
  • Why is Dalton’s Law important to divers?
dalton s law9
Dalton’s Law
  • Why is Dalton’s Law important to divers?
  • A diver breathing from a tank containing a gas, or contaminate, which is easily tolerated at the surface may experience problems as the partial pressure increases with depth
henry s law
Henry’s Law
  • “The amount of any given gas that will dissolve in a liquid at a given temperature is proportional to the partial pressure of that gas in equilibrium with the liquid and the solubility coefficient of the gas in the particular liquid”
henry s law1
Henry’s Law
  • In other words: If one unit of gas is dissolved at one atm, then two units will be dissolved at two atm, three at three atm, etc.
henry s law2
Henry’s Law
  • Stated mathematically:

VG

____________

VL

=  P1

henry s law3
Henry’s Law
  • Where:
    • VG = Volume of gas dissolved at STPD (standard temperature pressure dry)
    • VL = Volume of the liquid
    •  = Solubility coefficient at specified temperatures
    • P1 = Partial pressure of that gas above the liquid
henry s law4
Henry’s Law
  • When a gas-free liquid is first exposed to a gas mixture, gas molecules will diffuse into the solution, pushed by the partial pressure of each individual gas
henry s law5
Henry’s Law
  • As the gas molecules enter the liquid, they add to a state of “gas tension”
    • Gas tension is a way of identifying the partial pressure of the gas in the liquid
henry s law6
Henry’s Law
  • The difference between the gas tension and the partial pressure outside the liquid is called the pressure gradient
    • This gives an indication of the net rate the gas tends to enter or leave the solution
henry s law7
Henry’s Law
  • When the pressure gradient is high (low tension & high partial pressure), the rate of absorption into the liquid is high
henry s law8
Henry’s Law
  • As the number of gas molecules in the liquid increases, the gas tension increases until it reaches equilibrium with the outside partial pressure
  • At this point, the liquid is “saturated” with gas molecules, and the pressure gradient is zero
henry s law9
Henry’s Law
  • Unless there is a change in temperature or pressure, the net rate at which gas molecules enter or leave a saturated liquid is zero
henry s law10
Henry’s Law
  • How does Henry’s Law apply to divers?
henry s law11
Henry’s Law
  • How does Henry’s Law apply to divers?
  • The deeper one dives, the greater the pressure, the higher the total pressure of the breathing gas, and the more gas molecules are absorbed into tissues toward the equilibrium of saturation
henry s law12
Henry’s Law
  • How does Henry’s Law apply to divers?
  • As the diver ascends, the pressure gradient reverses and the gas molecules begin to leave the diver’s tissues
henry s law13
Henry’s Law
  • How does Henry’s Law apply to divers?
  • If the diver’s ascent rate is controlled properly, and all goes well, the excess gas molecules exit the diver’s body via the lungs
  • If not, gas bubbles may form, producing decompression sickness
general gas law ideal gas law
General Gas Law (Ideal Gas Law)
  • The General Gas Law is a combination of Charles’ and Boyle’s laws
  • It is used to predict the behavior of a given quantity of gas when changes may be expected in any or all of the variables (pressure, temperature, volume)
general gas law
General Gas Law
  • Stated mathematically:

P1 V1

________

T1

P2 V2

________

T2

=

general gas law1
General Gas Law
  • Where:
    • P1 = initial pressure (absolute)
    • V1 = initial volume
    • T1 = initial temperature (absolute)
    • P2 = final pressure (absolute)
    • V2 = final volume
    • T2 = final temperature (absolute)
general gas law2
General Gas Law
  • An open-bottom diving bell of 24 ft3 capacity is lowered to 99 fsw. The surface temperature is 80oF the temperature at depth is 45oF. What is the volume of the gas of the bell at depth?
general gas law3
General Gas Law
  • P1 = 14.7 psia
  • V1 = 24 ft3
  • T1 = 80oF + 460 = 540 Rankine
  • P2 = 58.8 psia
  • T2 = 45oF + 460 = 505 Rankine
  • V2 = Unknown
general gas law4
General Gas Law

P1 V1 T2

___________________________

T1 P2

V2 =

general gas law5
General Gas Law

(14.7 psia)(24ft3)(505 R)

____________________________________________________________

(540 R)(58.8 psia)

V2 =

general gas law6
General Gas Law

V2 = 5.61 ft3

moisture in breathing gas
Moisture In Breathing Gas
  • Breathing gas should have sufficient moisture for comfort
    • Too much moisture can increase breathing resistance and produce lung congestion
    • Too little moisture can cause an uncomfortable sensation of dryness when breathed
moisture in breathing gas1
Moisture In Breathing Gas
  • Gasses supplied from surface compressors or tanks can be assumed to be dry
humidity
Humidity
  • Water vapor (a gas) behaves in accordance with the gas laws; it condenses at temperatures we are likely to encounter while diving
humidity1
Humidity
  • When water vapor condenses it can produce:
    • Condensation in the breathing hoses or mask
      • This can be a problem in very cold (freezing) conditions
    • Fogging of the mask
      • Can be prevented with saliva, liquid soap, or commercial anti-fogging products
light
Light
  • Eyes function by collecting light that is emitted or reflected by an object – objects that absorb light appear colored
light1
Light
  • Water slows light - causing light to refract (bend) as it enters or leaves water. Light bends again when entering a mask. This creates distortion:
    • objects appear 25% larger
    • at distances of less than 4 feet, objects appear closer - at distances greater than 4 feet, objects appear farther
colors
Colors
  • Color is absorbed by light according to its wavelength – the deeper the water, the more light is absorbed
    • Red is absorbed first, followed by orange, yellow, and green. In very deep water blue and violet may be the only colors visible
  • Sunlight may penetrate to depths of 2000 ft
sound
Sound
  • Sound is produced by pressure waves triggered by vibration
  • The more dense the medium through which sound travels, the faster its speed
    • Speed of sound through air: 1,125 ft/second
    • Speed of sound through salt water: 5,023 ft/second
    • Speed of sound through steel: 16,600 ft/second
  • Almost impossible to determine the direction from which sound originates underwater
study questions
Study Questions
  • Use the following study questions to review some of the information presented in this self-study module
  • When you are finished you can print out your study questions results
self study questions
Self-study Questions

Select all that apply to "atmospheric pressure". There are at least three correct answers. (Select all that apply to atmospheric pressure)

  • 14.7 psi
  • Decreases with altitude
  • 1 atm
  • The force acting on a unit area
  • Increases with water depth
  • Pressure due to the weight of water
  • The pressure exerted by a single gas in a mixture
self study questions1
Self-study Questions

Select all that apply to "atmospheric pressure". There are at least three correct answers. (Select all that apply to atmospheric pressure)

  • 14.7 psi
  • Decreases with altitude
  • 1 atm
  • The force acting on a unit area
  • Increases with water depth
  • Pressure due to the weight of water
  • The pressure exerted by a single gas in a mixture
self study questions2
Self-study Questions

Select all that apply to "hydrostatic pressure". There are at least four correct answers.

  • The force acting on a unit area
  • .445 psi per foot seawater
  • Increases with water depth
  • Pressure due to the weight of water
  • .432 psi per foot fresh water
  • The sum of atmospheric and absolute pressures
  • The pressure exerted by a single gas in a gas mixture
  • Decreases with altitude
self study questions3
Self-study Questions

Select all that apply to "hydrostatic pressure". There are at least four correct answers.

  • The force acting on a unit area
  • .445 psi per foot seawater
  • Increases with water depth
  • Pressure due to the weight of water
  • .432 psi per foot fresh water
  • The sum of atmospheric and absolute pressures
  • The pressure exerted by a single gas in a gas mixture
  • Decreases with altitude
self study questions4
Self-study Questions

Select all that apply to "absolute pressure. There are at least three correct answers.

  • The sum of atmospheric and hydrostatic pressures
  • Increases with water depth
  • Ata
  • The difference between atmospheric pressure being measured
  • Pressure due to the weight of water
  • The pressure exerted by a single gas in a gas mixture
self study questions5
Self-study Questions

Select all that apply to "absolute pressure. There are at least three correct answers.

  • The sum of atmospheric and hydrostatic pressures
  • Increases with water depth
  • Ata
  • The difference between atmospheric pressure being measured
  • Pressure due to the weight of water
  • The pressure exerted by a single gas in a gas mixture
self study questions6
Self-study Questions

Select all that apply to "gauge pressure. There are at least three correct answers.

  • The difference between atmospheric pressure and the pressure being measured
  • Ata minus 14.7
  • Increases with water depth
  • The sum of atmospheric and hydrostatic pressure
  • The pressure exerted by a single gas in a gas mixture
  • The force acting on a unit of area squared
  • .432 psi per foot seawater
self study questions7
Self-study Questions

Select all that apply to "gauge pressure. There are at least three correct answers.

  • The difference between atmospheric pressure and the pressure being measured
  • Ata minus 14.7
  • Increases with water depth
  • The sum of atmospheric and hydrostatic pressure
  • The pressure exerted by a single gas in a gas mixture
  • The force acting on a unit of area squared
  • .432 psi per foot seawater
self study questions8
Self-study Questions

As depth increases the ______ of the breathing gas increases.

  • Density
  • Specific gravity
  • pH
  • volume
self study questions9
Self-study Questions

As depth increases the ______ of the breathing gas increases.

  • Density
  • Specific gravity
  • pH
  • volume
self study questions10
Self-study Questions

Specific gravity is the ratio of the weight of a given volume of a substance (density) to that of an equal volume of another substance.

  • True
  • False
self study questions11
Self-study Questions

Specific gravity is the ratio of the weight of a given volume of a substance (density) to that of an equal volume of another substance.

  • True
  • False
self study questions12
Self-study Questions

Select all that apply to "freshwater". There are at least three correct answers.

a. Has a density of 62.4 pounds per cubic foot

b. Has a density of 64 pounds per cubic foot

c. Freezes at 32 degrees F (0C), and boils at 212 degrees F (100C).

d. In its purest form, is a poor conductor of electricity

e. Contains almost every substance known

f. Is a good conductor of electricity

self study questions13
Self-study Questions

Select all that apply to "freshwater". There are at least three correct answers.

a. Has a density of 62.4 pounds per cubic foot

b. Has a density of 64 pounds per cubic foot

c. Freezes at 32 degrees F (0C), and boils at 212 degrees F (100C).

d. In its purest form, is a poor conductor of electricity

e. Contains almost every substance known

f. Is a good conductor of electricity

self study questions14
Self-study Questions

Select all that apply to "seawater". There are at least three correct answers.

  • Has a density of 62.4 pounds per cubic foot
  • Has a density of 64 pounds per cubic foot
  • Freezes at 32 degrees F (0C)
  • In its purest form, is a poor conductor of electricity
  • Contains almost every substance known
  • Is a good conductor of electricity
self study questions15
Self-study Questions

Select all that apply to "seawater". There are at least three correct answers.

  • Has a density of 62.4 pounds per cubic foot
  • Has a density of 64 pounds per cubic foot
  • Freezes at 32 degrees F (0C)
  • In its purest form, is a poor conductor of electricity
  • Contains almost every substance known
  • Is a good conductor of electricity
self study questions16
Self-study Questions

One meter equals 3.28 feet. Convert 25 feet to meters.

  • 7.62
  • 82
  • 6
  • 25
self study questions17
Self-study Questions

One meter equals 3.28 feet. Convert 25 feet to meters.

  • 7.62
  • 82
  • 6
  • 25
self study questions18
Self-study Questions

One meter equals 3.28 feet. Convert 50 meters to feet.

  • 164
  • 15.24
  • 150
  • 50
self study questions19
Self-study Questions

One meter equals 3.28 feet. Convert 50 meters to feet.

  • 164
  • 15.24
  • 150
  • 50
self study questions20
Self-study Questions

Match the English and International temperature scale with its absolute temperature counterpart.

  • Fahrenheit Rankine
  • Celsius Kelvin
self study questions21
Self-study Questions

Match the English and International temperature scale with its absolute temperature counterpart.

  • Fahrenheit Rankine
  • Celsius Kelvin
self study questions22
Self-study Questions

Match the choice with its definition.

Archimedes' Principle

Boyle's Law

Charles' Law

Dalton's Law

Henry's Law

General Gas Law

Positive Buoyancy

Negative Buoyancy

Neutral Buoyancy

A. Any object wholly or partly immersed in a fluid is buoyed up by a force equal to the weight of the fluid displaced by the object.

B. For any gas at a constant temperature, the volume of the gas will vary inversely with the pressure.

C. For any gas at a constant pressure, the volume of the gas will vary directly with the absolute temperature or for any gas at a constant volume, the pressure of the gas will vary directly with the absolute temperature.

D. The total pressure exerted by a mixture of gases is equal to the sum of the pressures of each of the different gases making up the mixture, with each gas acting as if it alone was present and occupied the total volume.

E. The amount of any given gas that will dissolve in a liquid at a given temperature is proportional to the partial pressure of that gas in equilibrium with the liquid and the solubility coefficient of the gas in the particular liquid.

F. A combination of Charles’ and Boyle’s laws; it is used to predict the behavior of a given quantity of gas when changes may be expected in any or all of the variables (pressure, temperature, volume).

G. When the weight of the displaced fluid is greater than the submerged object.

H. When the weight of the displaced fluid is less than the weight of the submerged object.

I. When the weight of the object is equal to the weight of the fluid displaced.

self study questions23
Self-study Questions

Match the choice with its definition.

Archimedes' Principle

Boyle's Law

Charles' Law

Dalton's Law

Henry's Law

General Gas Law

Positive Buoyancy

Negative Buoyancy

Neutral Buoyancy

A. Any object wholly or partly immersed in a fluid is buoyed up by a force equal to the weight of the fluid displaced by the object.

B. For any gas at a constant temperature, the volume of the gas will vary inversely with the pressure.

C. For any gas at a constant pressure, the volume of the gas will vary directly with the absolute temperature or for any gas at a constant volume, the pressure of the gas will vary directly with the absolute temperature.

D. The total pressure exerted by a mixture of gases is equal to the sum of the pressures of each of the different gases making up the mixture, with each gas acting as if it alone was present and occupied the total volume.

E. The amount of any given gas that will dissolve in a liquid at a given temperature is proportional to the partial pressure of that gas in equilibrium with the liquid and the solubility coefficient of the gas in the particular liquid.

F. A combination of Charles’ and Boyle’s laws; it is used to predict the behavior of a given quantity of gas when changes may be expected in any or all of the variables (pressure, temperature, volume).

G. When the weight of the displaced fluid is greater than the submerged object.

H. When the weight of the displaced fluid is less than the weight of the submerged object.

I. When the weight of the object is equal to the weight of the fluid displaced.

self study questions24
Self-study Questions

Match the choice with its definition.

Archimedes' Principle

Boyle's Law

Charles' Law

Dalton's Law

Henry's Law

General Gas Law

Positive Buoyancy

Negative Buoyancy

Neutral Buoyancy

A. Any object wholly or partly immersed in a fluid is buoyed up by a force equal to the weight of the fluid displaced by the object.

B. For any gas at a constant temperature, the volume of the gas will vary inversely with the pressure.

C. For any gas at a constant pressure, the volume of the gas will vary directly with the absolute temperature or for any gas at a constant volume, the pressure of the gas will vary directly with the absolute temperature.

D. The total pressure exerted by a mixture of gases is equal to the sum of the pressures of each of the different gases making up the mixture, with each gas acting as if it alone was present and occupied the total volume.

E. The amount of any given gas that will dissolve in a liquid at a given temperature is proportional to the partial pressure of that gas in equilibrium with the liquid and the solubility coefficient of the gas in the particular liquid.

F. A combination of Charles’ and Boyle’s laws; it is used to predict the behavior of a given quantity of gas when changes may be expected in any or all of the variables (pressure, temperature, volume).

G. When the weight of the displaced fluid is greater than the submerged object.

H. When the weight of the displaced fluid is less than the weight of the submerged object.

I. When the weight of the object is equal to the weight of the fluid displaced.

self study questions25
Self-study Questions

Match the choice with its definition.

Archimedes' Principle

Boyle's Law

Charles' Law

Dalton's Law

Henry's Law

General Gas Law

Positive Buoyancy

Negative Buoyancy

Neutral Buoyancy

A. Any object wholly or partly immersed in a fluid is buoyed up by a force equal to the weight of the fluid displaced by the object.

B. For any gas at a constant temperature, the volume of the gas will vary inversely with the pressure.

C. For any gas at a constant pressure, the volume of the gas will vary directly with the absolute temperature or for any gas at a constant volume, the pressure of the gas will vary directly with the absolute temperature.

D. The total pressure exerted by a mixture of gases is equal to the sum of the pressures of each of the different gases making up the mixture, with each gas acting as if it alone was present and occupied the total volume.

E. The amount of any given gas that will dissolve in a liquid at a given temperature is proportional to the partial pressure of that gas in equilibrium with the liquid and the solubility coefficient of the gas in the particular liquid.

F. A combination of Charles’ and Boyle’s laws; it is used to predict the behavior of a given quantity of gas when changes may be expected in any or all of the variables (pressure, temperature, volume).

G. When the weight of the displaced fluid is greater than the submerged object.

H. When the weight of the displaced fluid is less than the weight of the submerged object.

I. When the weight of the object is equal to the weight of the fluid displaced.

self study questions26
Self-study Questions

Match the choice with its definition.

Archimedes' Principle

Boyle's Law

Charles' Law

Dalton's Law

Henry's Law

General Gas Law

Positive Buoyancy

Negative Buoyancy

Neutral Buoyancy

A.Any object wholly or partly immersed in a fluid is buoyed up by a force equal to the weight of the fluid displaced by the object.

B. For any gas at a constant temperature, the volume of the gas will vary inversely with the pressure.

C. For any gas at a constant pressure, the volume of the gas will vary directly with the absolute temperature or for any gas at a constant volume, the pressure of the gas will vary directly with the absolute temperature.

D. The total pressure exerted by a mixture of gases is equal to the sum of the pressures of each of the different gases making up the mixture, with each gas acting as if it alone was present and occupied the total volume.

E. The amount of any given gas that will dissolve in a liquid at a given temperature is proportional to the partial pressure of that gas in equilibrium with the liquid and the solubility coefficient of the gas in the particular liquid.

F. A combination of Charles’ and Boyle’s laws; it is used to predict the behavior of a given quantity of gas when changes may be expected in any or all of the variables (pressure, temperature, volume).

G. When the weight of the displaced fluid is greater than the submerged object.

H. When the weight of the displaced fluid is less than the weight of the submerged object.

I. When the weight of the object is equal to the weight of the fluid displaced.

self study questions27
Self-study Questions

Match the choice with its definition.

Archimedes' Principle

Boyle's Law

Charles' Law

Dalton's Law

Henry's Law

General Gas Law

Positive Buoyancy

Negative Buoyancy

Neutral Buoyancy

A. Any object wholly or partly immersed in a fluid is buoyed up by a force equal to the weight of the fluid displaced by the object.

B. For any gas at a constant temperature, the volume of the gas will vary inversely with the pressure.

C. For any gas at a constant pressure, the volume of the gas will vary directly with the absolute temperature or for any gas at a constant volume, the pressure of the gas will vary directly with the absolute temperature.

D. The total pressure exerted by a mixture of gases is equal to the sum of the pressures of each of the different gases making up the mixture, with each gas acting as if it alone was present and occupied the total volume.

E. The amount of any given gas that will dissolve in a liquid at a given temperature is proportional to the partial pressure of that gas in equilibrium with the liquid and the solubility coefficient of the gas in the particular liquid.

F. A combination of Charles’ and Boyle’s laws; it is used to predict the behavior of a given quantity of gas when changes may be expected in any or all of the variables (pressure, temperature, volume).

G. When the weight of the displaced fluid is greater than the submerged object.

H. When the weight of the displaced fluid is less than the weight of the submerged object.

I. When the weight of the object is equal to the weight of the fluid displaced.

self study questions28
Self-study Questions

Match the choice with its definition.

Archimedes' Principle

Boyle's Law

Charles' Law

Dalton's Law

Henry's Law

General Gas Law

Positive Buoyancy

Negative Buoyancy

Neutral Buoyancy

A. Any object wholly or partly immersed in a fluid is buoyed up by a force equal to the weight of the fluid displaced by the object.

B. For any gas at a constant temperature, the volume of the gas will vary inversely with the pressure.

C. For any gas at a constant pressure, the volume of the gas will vary directly with the absolute temperature or for any gas at a constant volume, the pressure of the gas will vary directly with the absolute temperature.

D. The total pressure exerted by a mixture of gases is equal to the sum of the pressures of each of the different gases making up the mixture, with each gas acting as if it alone was present and occupied the total volume.

E. The amount of any given gas that will dissolve in a liquid at a given temperature is proportional to the partial pressure of that gas in equilibrium with the liquid and the solubility coefficient of the gas in the particular liquid.

F. A combination of Charles’ and Boyle’s laws; it is used to predict the behavior of a given quantity of gas when changes may be expected in any or all of the variables (pressure, temperature, volume).

G. When the weight of the displaced fluid is greater than the submerged object.

H. When the weight of the displaced fluid is less than the weight of the submerged object.

I. When the weight of the object is equal to the weight of the fluid displaced.

self study questions29
Self-study Questions

Match the choice with its definition.

Archimedes' Principle

Boyle's Law

Charles' Law

Dalton's Law

Henry's Law

General Gas Law

Positive Buoyancy

Negative Buoyancy

Neutral Buoyancy

A. Any object wholly or partly immersed in a fluid is buoyed up by a force equal to the weight of the fluid displaced by the object.

B. For any gas at a constant temperature, the volume of the gas will vary inversely with the pressure.

C. For any gas at a constant pressure, the volume of the gas will vary directly with the absolute temperature or for any gas at a constant volume, the pressure of the gas will vary directly with the absolute temperature.

D. The total pressure exerted by a mixture of gases is equal to the sum of the pressures of each of the different gases making up the mixture, with each gas acting as if it alone was present and occupied the total volume.

E. The amount of any given gas that will dissolve in a liquid at a given temperature is proportional to the partial pressure of that gas in equilibrium with the liquid and the solubility coefficient of the gas in the particular liquid.

F. A combination of Charles’ and Boyle’s laws; it is used to predict the behavior of a given quantity of gas when changes may be expected in any or all of the variables (pressure, temperature, volume).

G. When the weight of the displaced fluid is greater than the submerged object.

H. When the weight of the displaced fluid is less than the weight of the submerged object.

I. When the weight of the object is equal to the weight of the fluid displaced.

self study questions30
Self-study Questions

Match the choice with its definition.

Archimedes' Principle

Boyle's Law

Charles' Law

Dalton's Law

Henry's Law

General Gas Law

Positive Buoyancy

Negative Buoyancy

Neutral Buoyancy

A. Any object wholly or partly immersed in a fluid is buoyed up by a force equal to the weight of the fluid displaced by the object.

B. For any gas at a constant temperature, the volume of the gas will vary inversely with the pressure.

C. For any gas at a constant pressure, the volume of the gas will vary directly with the absolute temperature or for any gas at a constant volume, the pressure of the gas will vary directly with the absolute temperature.

D. The total pressure exerted by a mixture of gases is equal to the sum of the pressures of each of the different gases making up the mixture, with each gas acting as if it alone was present and occupied the total volume.

E. The amount of any given gas that will dissolve in a liquid at a given temperature is proportional to the partial pressure of that gas in equilibrium with the liquid and the solubility coefficient of the gas in the particular liquid.

F. A combination of Charles’ and Boyle’s laws; it is used to predict the behavior of a given quantity of gas when changes may be expected in any or all of the variables (pressure, temperature, volume).

G. When the weight of the displaced fluid is greater than the submerged object.

H. When the weight of the displaced fluid is less than the weight of the submerged object.

I. When the weight of the object is equal to the weight of the fluid displaced.

self study questions31
Self-study Questions

Match the choice with its definition.

Archimedes' Principle

Boyle's Law

Charles' Law

Dalton's Law

Henry's Law

General Gas Law

Positive Buoyancy

Negative Buoyancy

Neutral Buoyancy

A. Any object wholly or partly immersed in a fluid is buoyed up by a force equal to the weight of the fluid displaced by the object.

B. For any gas at a constant temperature, the volume of the gas will vary inversely with the pressure.

C. For any gas at a constant pressure, the volume of the gas will vary directly with the absolute temperature or for any gas at a constant volume, the pressure of the gas will vary directly with the absolute temperature.

D. The total pressure exerted by a mixture of gases is equal to the sum of the pressures of each of the different gases making up the mixture, with each gas acting as if it alone was present and occupied the total volume.

E. The amount of any given gas that will dissolve in a liquid at a given temperature is proportional to the partial pressure of that gas in equilibrium with the liquid and the solubility coefficient of the gas in the particular liquid.

F. A combination of Charles’ and Boyle’s laws; it is used to predict the behavior of a given quantity of gas when changes may be expected in any or all of the variables (pressure, temperature, volume).

G. When the weight of the displaced fluid is greater than the submerged object.

H. When the weight of the displaced fluid is less than the weight of the submerged object.

I. When the weight of the object is equal to the weight of the fluid displaced.

self study questions32
Self-study Questions

Select all that apply to "air". There are at least two correct answers.

A. the most common gas breathed underwater

B. it is composed of approximately 78% Nitrogen, 21% Oxygen, and 1% other gases

C. has a major role in decompression

D. is a natural by-product of metabolism

E. is produced by incomplete combustion of fuels and is found in the exhaust of internal-combustion engines and overheated oil-lubricated compressors

F. is required for human life

self study questions33
Self-study Questions

Select all that apply to "air". There are at least two correct answers.

A. the most common gas breathed underwater

B. it is composed of approximately 78% Nitrogen, 21% Oxygen, and 1% other gases

C.has a major role in decompression

D. is a natural by-product of metabolism

E. is produced by incomplete combustion of fuels and is found in the exhaust of internal-combustion engines and overheated oil-lubricated compressors

F. is required for human life

self study questions34
Self-study Questions

Match the gas with its characteristic.

Oxygen

Nitrogen

Helium

Carbon Dioxide

Carbon Monoxide

Argon

Neon

Hydrogen

A. is required for human life

B. has the major role in decompression; as the partial pressure increases with depth, it produces an intoxicated state that is characterized by loss of judgment and disorientation

C. is used extensively in deep diving; it has a lower density that reduces breathing resistance; disadvantages include “Donald Duck” voice and heat loss due to its high thermal conductivity

D. is a natural by-product of metabolism; can cause unconsciousness that can be fatal in divers; elevated levels may further predispose a diver to nitrogen narcosis, oxygen toxicity, and decompression sickness

E. a poisonous gas which interferes with the blood’s ability to carry oxygen; is produced by the incomplete combustion of fuels and is found in the exhaust of internal-combustion engines and overheated oil-lubricated compressors

F. has narcotic properties and a density that make it inappropriate as a breathing gas; is frequently used to inflate dry suits because its higher density reduces conduction of heat

G. causes less voice distortion than helium and has lower thermal conductivity; is expensive and causes increased breathing resistance under work load

H. is readily available and produces less breathing resistance at depth than other gases; its major disadvantage is that is explosive

self study questions35
Self-study Questions

Match the gas with its characteristic.

Oxygen

Nitrogen

Helium

Carbon Dioxide

Carbon Monoxide

Argon

Neon

Hydrogen

A. is required for human life

B. has the major role in decompression; as the partial pressure increases with depth, it produces an intoxicated state that is characterized by loss of judgment and disorientation

C. is used extensively in deep diving; it has a lower density that reduces breathing resistance; disadvantages include “Donald Duck” voice and heat loss due to its high thermal conductivity

D. is a natural by-product of metabolism; can cause unconsciousness that can be fatal in divers; elevated levels may further predispose a diver to nitrogen narcosis, oxygen toxicity, and decompression sickness

E. a poisonous gas which interferes with the blood’s ability to carry oxygen; is produced by the incomplete combustion of fuels and is found in the exhaust of internal-combustion engines and overheated oil-lubricated compressors

F. has narcotic properties and a density that make it inappropriate as a breathing gas; is frequently used to inflate dry suits because its higher density reduces conduction of heat

G. causes less voice distortion than helium and has lower thermal conductivity; is expensive and causes increased breathing resistance under work load

H. is readily available and produces less breathing resistance at depth than other gases; its major disadvantage is that is explosive

self study questions36
Self-study Questions

Match the gas with its characteristic.

Oxygen

Nitrogen

Helium

Carbon Dioxide

Carbon Monoxide

Argon

Neon

Hydrogen

A. is required for human life

B. has the major role in decompression; as the partial pressure increases with depth, it produces an intoxicated state that is characterized by loss of judgment and disorientation

C. is used extensively in deep diving; it has a lower density that reduces breathing resistance; disadvantages include “Donald Duck” voice and heat loss due to its high thermal conductivity

D. is a natural by-product of metabolism; can cause unconsciousness that can be fatal in divers; elevated levels may further predispose a diver to nitrogen narcosis, oxygen toxicity, and decompression sickness

E. a poisonous gas which interferes with the blood’s ability to carry oxygen; is produced by the incomplete combustion of fuels and is found in the exhaust of internal-combustion engines and overheated oil-lubricated compressors

F. has narcotic properties and a density that make it inappropriate as a breathing gas; is frequently used to inflate dry suits because its higher density reduces conduction of heat

G. causes less voice distortion than helium and has lower thermal conductivity; is expensive and causes increased breathing resistance under work load

H. is readily available and produces less breathing resistance at depth than other gases; its major disadvantage is that is explosive

self study questions37
Self-study Questions

Match the gas with its characteristic.

Oxygen

Nitrogen

Helium

Carbon Dioxide

Carbon Monoxide

Argon

Neon

Hydrogen

A. is required for human life

B. has the major role in decompression; as the partial pressure increases with depth, it produces an intoxicated state that is characterized by loss of judgment and disorientation

C. is used extensively in deep diving; it has a lower density that reduces breathing resistance; disadvantages include “Donald Duck” voice and heat loss due to its high thermal conductivity

D. is a natural by-product of metabolism; can cause unconsciousness that can be fatal in divers; elevated levels may further predispose a diver to nitrogen narcosis, oxygen toxicity, and decompression sickness

E. a poisonous gas which interferes with the blood’s ability to carry oxygen; is produced by the incomplete combustion of fuels and is found in the exhaust of internal-combustion engines and overheated oil-lubricated compressors

F. has narcotic properties and a density that make it inappropriate as a breathing gas; is frequently used to inflate dry suits because its higher density reduces conduction of heat

G. causes less voice distortion than helium and has lower thermal conductivity; is expensive and causes increased breathing resistance under work load

H. is readily available and produces less breathing resistance at depth than other gases; its major disadvantage is that is explosive

self study questions38
Self-study Questions

Match the gas with its characteristic.

Oxygen

Nitrogen

Helium

Carbon Dioxide

Carbon Monoxide

Argon

Neon

Hydrogen

A. is required for human life

B. has the major role in decompression; as the partial pressure increases with depth, it produces an intoxicated state that is characterized by loss of judgment and disorientation

C. is used extensively in deep diving; it has a lower density that reduces breathing resistance; disadvantages include “Donald Duck” voice and heat loss due to its high thermal conductivity

D. is a natural by-product of metabolism; can cause unconsciousness that can be fatal in divers; elevated levels may further predispose a diver to nitrogen narcosis, oxygen toxicity, and decompression sickness

E. a poisonous gas which interferes with the blood’s ability to carry oxygen; is produced by the incomplete combustion of fuels and is found in the exhaust of internal-combustion engines and overheated oil-lubricated compressors

F. has narcotic properties and a density that make it inappropriate as a breathing gas; is frequently used to inflate dry suits because its higher density reduces conduction of heat

G. causes less voice distortion than helium and has lower thermal conductivity; is expensive and causes increased breathing resistance under work load

H. is readily available and produces less breathing resistance at depth than other gases; its major disadvantage is that is explosive

self study questions39
Self-study Questions

Match the gas with its characteristic.

Oxygen

Nitrogen

Helium

Carbon Dioxide

Carbon Monoxide

Argon

Neon

Hydrogen

A. is required for human life

B. has the major role in decompression; as the partial pressure increases with depth, it produces an intoxicated state that is characterized by loss of judgment and disorientation

C. is used extensively in deep diving; it has a lower density that reduces breathing resistance; disadvantages include “Donald Duck” voice and heat loss due to its high thermal conductivity

D. is a natural by-product of metabolism; can cause unconsciousness that can be fatal in divers; elevated levels may further predispose a diver to nitrogen narcosis, oxygen toxicity, and decompression sickness

E. a poisonous gas which interferes with the blood’s ability to carry oxygen; is produced by the incomplete combustion of fuels and is found in the exhaust of internal-combustion engines and overheated oil-lubricated compressors

F. has narcotic properties and a density that make it inappropriate as a breathing gas; is frequently used to inflate dry suits because its higher density reduces conduction of heat

G. causes less voice distortion than helium and has lower thermal conductivity; is expensive and causes increased breathing resistance under work load

H. is readily available and produces less breathing resistance at depth than other gases; its major disadvantage is that is explosive

self study questions40
Self-study Questions

Match the gas with its characteristic.

Oxygen

Nitrogen

Helium

Carbon Dioxide

Carbon Monoxide

Argon

Neon

Hydrogen

A. is required for human life

B. has the major role in decompression; as the partial pressure increases with depth, it produces an intoxicated state that is characterized by loss of judgment and disorientation

C. is used extensively in deep diving; it has a lower density that reduces breathing resistance; disadvantages include “Donald Duck” voice and heat loss due to its high thermal conductivity

D. is a natural by-product of metabolism; can cause unconsciousness that can be fatal in divers; elevated levels may further predispose a diver to nitrogen narcosis, oxygen toxicity, and decompression sickness

E. a poisonous gas which interferes with the blood’s ability to carry oxygen; is produced by the incomplete combustion of fuels and is found in the exhaust of internal-combustion engines and overheated oil-lubricated compressors

F. has narcotic properties and a density that make it inappropriate as a breathing gas; is frequently used to inflate dry suits because its higher density reduces conduction of heat

G. causes less voice distortion than helium and has lower thermal conductivity; is expensive and causes increased breathing resistance under work load

H. is readily available and produces less breathing resistance at depth than other gases; its major disadvantage is that is explosive

self study questions41
Self-study Questions

Match the gas with its characteristic.

Oxygen

Nitrogen

Helium

Carbon Dioxide

Carbon Monoxide

Argon

Neon

Hydrogen

A. is required for human life

B. has the major role in decompression; as the partial pressure increases with depth, it produces an intoxicated state that is characterized by loss of judgment and disorientation

C. is used extensively in deep diving; it has a lower density that reduces breathing resistance; disadvantages include “Donald Duck” voice and heat loss due to its high thermal conductivity

D. is a natural by-product of metabolism; can cause unconsciousness that can be fatal in divers; elevated levels may further predispose a diver to nitrogen narcosis, oxygen toxicity, and decompression sickness

E. a poisonous gas which interferes with the blood’s ability to carry oxygen; is produced by the incomplete combustion of fuels and is found in the exhaust of internal-combustion engines and overheated oil-lubricated compressors

F. has narcotic properties and a density that make it inappropriate as a breathing gas; is frequently used to inflate dry suits because its higher density reduces conduction of heat

G. causes less voice distortion than helium and has lower thermal conductivity; is expensive and causes increased breathing resistance under work load

H. is readily available and produces less breathing resistance at depth than other gases; its major disadvantage is that is explosive

self study questions42
Self-study Questions

Match the gas with its characteristic.

Oxygen

Nitrogen

Helium

Carbon Dioxide

Carbon Monoxide

Argon

Neon

Hydrogen

A. is required for human life

B. has the major role in decompression; as the partial pressure increases with depth, it produces an intoxicated state that is characterized by loss of judgment and disorientation

C. is used extensively in deep diving; it has a lower density that reduces breathing resistance; disadvantages include “Donald Duck” voice and heat loss due to its high thermal conductivity

D. is a natural by-product of metabolism; can cause unconsciousness that can be fatal in divers; elevated levels may further predispose a diver to nitrogen narcosis, oxygen toxicity, and decompression sickness

E. a poisonous gas which interferes with the blood’s ability to carry oxygen; is produced by the incomplete combustion of fuels and is found in the exhaust of internal-combustion engines and overheated oil-lubricated compressors

F. has narcotic properties and a density that make it inappropriate as a breathing gas; is frequently used to inflate dry suits because its higher density reduces conduction of heat

G. causes less voice distortion than helium and has lower thermal conductivity; is expensive and causes increased breathing resistance under work load

H. is readily available and produces less breathing resistance at depth than other gases; its major disadvantage is that is explosive

self study questions43
Self-study Questions

Too much moisture in the diver's breathing gas can decrease breathing resistance.

  • True
  • False
self study questions44
Self-study Questions

Too much moisture in the diver's breathing gas can decrease breathing resistance.

  • True
  • False
self study questions45
Self-study Questions

Humidity in the form of condensation in the breathing hoses or mask can be a problem in very cold (freezing) conditions.

  • True
  • False
self study questions46
Self-study Questions

Humidity in the form of condensation in the breathing hoses or mask can be a problem in very cold (freezing) conditions.

  • True
  • False
self study questions47
Self-study Questions

Water slows light - causing light to _______ as it enters or leaves water. This creates distortion making objects appear larger and, at distances less than 4 feet, closer.

  • Refract
  • Magnify
  • Be absorbed
  • diffuse
self study questions48
Self-study Questions

Water slows light - causing light to _______ as it enters or leaves water. This creates distortion making objects appear larger and, at distances less than 4 feet, closer.

  • Refract
  • Magnify
  • Be absorbed
  • diffuse
self study questions49
Self-study Questions

The more dense the medium through which sound travels, the ______.

  • Faster its speed
  • Slower its speed
self study questions50
Self-study Questions

The more dense the medium through which sound travels, the ______.

  • Faster its speed
  • Slower its speed
self study questions51
Self-study Questions

_____ is the first wavelength of light to be absorbed by water.

  • Red
  • Orange
  • Blue
  • Green
self study questions52
Self-study Questions

_____ is the first wavelength of light to be absorbed by water.

  • Red
  • Orange
  • Blue
  • Green
self study questions53
Self-study Questions

One ata of hydrostatic pressure is reached every ___ feet in seawater. (One ata of hydrostatic pressure is reached every ___ feet in seawater.)

  • 33
  • 34
  • .445
  • .432
self study questions54
Self-study Questions

One ata of hydrostatic pressure is reached every ___ feet in seawater. (One ata of hydrostatic pressure is reached every ___ feet in seawater.)

  • 33
  • 34
  • .445
  • .432