Physics of Diving Part 1
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Questions and Answers

What determines whether an object will float or sink in water?

  • The temperature of the water
  • The size of the object alone
  • The object's color and texture
  • The object's weight compared to water displacement (correct)

When a box weighing -40 kg is subjected to a net positive force of 0.17 lbs, what can be concluded?

  • The box is neutrally buoyant
  • The box will sink
  • The box will float (correct)
  • The box's buoyancy cannot be determined

How much lift is required to get a solid metal box weighing 200 lbs to the surface in saltwater?

  • 200 lbs of lift
  • 72 lbs of lift (correct)
  • 128 lbs of lift
  • 64 lbs of lift

What is the ultimate goal of an HPU scientific diver in terms of buoyancy?

<p>To achieve neutral buoyancy (A)</p> Signup and view all the answers

What should divers do if they find themselves sinking unexpectedly during a dive?

<p>Adjust their buoyancy compensator (BCD) (A)</p> Signup and view all the answers

When should a diver perform a weight check for proper weighting?

<p>At the beginning and end of the dive (B)</p> Signup and view all the answers

Why is it not advisable to simply add more weight while diving?

<p>All of the above (D)</p> Signup and view all the answers

What factor contributes to the variability of an individual's buoyancy underwater?

<p>Specific gravities of body tissues (B)</p> Signup and view all the answers

What does adding 1 ata to the pressure signify?

<p>Atmospheric pressure (A)</p> Signup and view all the answers

If the pressure at a certain depth is 2 ata and the volume is 10 unit volumes, what is the volume at 1 ata?

<p>10 unit volumes (B)</p> Signup and view all the answers

While descending to a depth where the pressure is 4 ata, how is the volume of gas affected?

<p>Volume decreases (A)</p> Signup and view all the answers

What factor must be accounted for when planning a dive regarding air consumption?

<p>Depth and personal air consumption (C)</p> Signup and view all the answers

What happens to the buoyant force when a diver exhales air?

<p>It decreases. (A)</p> Signup and view all the answers

Using Amontons' Law, what happens to the pressure if the temperature is doubled while volume remains constant?

<p>Pressure doubles (A)</p> Signup and view all the answers

At a depth of 66'/20m, if air volume consumption is said to triple, what is the pressure at this depth?

<p>3 ata (D)</p> Signup and view all the answers

How is specific gravity defined?

<p>The ratio of the density of a substance to that of a standard. (A)</p> Signup and view all the answers

If an object displaces 1 ft³ of seawater, what is the upward buoyant force?

<p>64 lbs (A)</p> Signup and view all the answers

To what does 'V1' represent in the reference to Boyle's Law?

<p>Initial gas volume at sea level (D)</p> Signup and view all the answers

If you have a gas volume of 4.5 volumes at 39'/11.8m and move to 102'/30.9m, what will be your new volume according to Boyle's Law?

<p>2.39 unit volumes (D)</p> Signup and view all the answers

What will happen to a 100 lbs sealed box that displaces 2 ft³ of water in saltwater?

<p>It will float. (D)</p> Signup and view all the answers

How much weight is equivalent to 1 liter of seawater?

<p>1.03 kg (C)</p> Signup and view all the answers

Which of the following objects will definitely sink in saltwater?

<p>A box that weighs 200 lbs and displaces 2 ft³ of water. (D)</p> Signup and view all the answers

What must be done to make an object negatively buoyant?

<p>Increase weight or downward force. (D)</p> Signup and view all the answers

What is the total upward force acting on a sealed box that weighs 40 kg and displaces 39 liters of water in saltwater?

<p>40.17 kg (D)</p> Signup and view all the answers

What is the total pressure exerted by a mixture of gases according to Dalton’s Law?

<p>The sum of the pressures of each gas making up the mixture (B)</p> Signup and view all the answers

For a diver breathing air at a depth of 33 feet, what is the partial pressure of Nitrogen?

<p>1.56 ata (A)</p> Signup and view all the answers

What percentage of Oxygen is used when calculating partial pressures for a diver breathing Enriched Air at 33 feet?

<p>40% (C)</p> Signup and view all the answers

Using Dalton’s Law, what is the total pressure exerted at a depth of 33 feet?

<p>2.00 ata (D)</p> Signup and view all the answers

What occurs to the pressure of a scuba cylinder when it is moved from a shaded area to direct sunlight?

<p>The pressure increases due to the rise in temperature. (D)</p> Signup and view all the answers

According to Henry’s Law, what happens when gas is dissolved in a liquid?

<p>Gas retains its pressure and intrinsic properties (D)</p> Signup and view all the answers

What does the term 'gas tension' refer to in the context of diving physiology?

<p>Pressure exerted by dissolved gas (C)</p> Signup and view all the answers

When converting Fahrenheit to Rankine, what is the formula used?

<p>Rankine = Fahrenheit + 459.67 (C)</p> Signup and view all the answers

According to Amontons' Law, what happens to the pressure as the temperature in a scuba cylinder increases?

<p>Pressure is directly proportional to the temperature. (D)</p> Signup and view all the answers

When calculating the partial pressures contributed by each gas in a mixture, which component is often the smallest?

<p>Other gases (A)</p> Signup and view all the answers

What would happen to the total pressure if a diver descended deeper than 33 feet?

<p>Total pressure would increase (A)</p> Signup and view all the answers

If a scuba cylinder is filled and its temperature rises, what is the effect on the pressure?

<p>The pressure will increase noticeably. (C)</p> Signup and view all the answers

How much does the pressure in a scuba cylinder typically change for each degree Fahrenheit increase?

<p>5-6 psi (A)</p> Signup and view all the answers

What temperature scale should be used for calculations involving Amontons' Law?

<p>Kelvin or Rankine (C)</p> Signup and view all the answers

How do Charles' Law and Amontons' Law relate to one another?

<p>They are both based on volume and temperature relationships. (B)</p> Signup and view all the answers

If a scuba cylinder initially contains 3000 psi at 70°F, what is the resulting pressure when it warms to 95°F?

<p>Approximately 3152 psi (C)</p> Signup and view all the answers

What characterizes a solid in the context of states of matter?

<p>It is structurally rigid and resistant to applied forces. (B)</p> Signup and view all the answers

Which principle explains the lifting needs in diving?

<p>Archimedes Principle (D)</p> Signup and view all the answers

What is the weight of 1 cubic foot of seawater?

<p>64 lbs (B)</p> Signup and view all the answers

Which equation represents the relationship between density, mass, and volume?

<p>d = m/v (B)</p> Signup and view all the answers

What does Boyle's Law describe concerning gases?

<p>The relationship between pressure and volume. (C)</p> Signup and view all the answers

What properties make water significantly different from air when diving?

<p>Density and compressibility. (D)</p> Signup and view all the answers

How does Dalton's Law apply to diving?

<p>It helps in calculating partial pressures of mixed gases. (A)</p> Signup and view all the answers

What is a unique property of a liquid state of matter?

<p>It flows freely with a constant volume. (C)</p> Signup and view all the answers

Flashcards

Buoyancy

A force that opposes the weight of an object submerged in a fluid, such as water.

Buoyant force

The upward force exerted by a fluid on an object submerged in it.

Neutral buoyancy

When the weight of an object is equal to the buoyant force acting on it.

Relative density

The ratio of the density of an object to the density of the fluid it is submerged in.

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Displacement

The amount of fluid an object displaces when submerged.

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Lift bag

A device used to provide additional buoyancy underwater.

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Pre-dive weight check

A weight check done at the beginning of a dive to ensure proper weighting.

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Post-dive weight check

A weight check done at the end of a dive to fine-tune buoyancy.

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Specific Gravity

The ratio of the density of a substance to the density of water.

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Volume Displaced

The volume of fluid the object displaces.

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Weight of the Object

The weight of an object submerged in a fluid.

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Force Of Gravity

The force exerted on an object due to gravity.

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Positive Buoyancy

When the buoyant force is greater than the weight of the object, causing it to float.

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Negative Buoyancy

When the weight of the object is greater than the buoyant force, causing it to sink.

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Buoyancy Calculation

A method to determine if an object will float or sink by comparing the buoyant force and object's weight.

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Solid

A state of matter characterized by rigidity and resistance to applied forces. Think of ice, it maintains its shape.

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Liquid

A state of matter that flows freely but maintains constant volume. It's nearly incompressible. Think of water, it fills a container but its volume is the same.

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Gas

A state of matter with molecules that are highly flexible and spread out. Think of air, it fills spaces and can be compressed.

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Density

The degree of compactness of a substance, often referred to as its "heaviness". It is calculated by dividing mass by volume. Formula: density = mass/volume or d = m/v

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Weight

The force exerted on a body by gravity. It's measured in units such as pounds or kilograms.

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Volume

The amount of space a substance or object occupies. It's generally measured in cubic units like cubic feet or liters.

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Mass

The total amount of matter contained in an object. It's measured in units of mass like pounds or kilograms.

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Amontons' Law

A law stating that the pressure of a gas is directly proportional to its absolute temperature when the volume is held constant.

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Charles' Law

A law stating that the absolute temperature and volume of a gas are directly proportional to each other when the pressure is constant.

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Fahrenheit to Rankine Conversion

The process of converting a temperature from degrees Fahrenheit to degrees Rankine.

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Celsius to Kelvin Conversion

The process of converting a temperature from degrees Celsius to degrees Kelvin.

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Atmospheres (atm)

The unit of pressure used in Amontons' Law calculations.

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Pounds per square inch (psi)

The unit of pressure commonly used in scuba gear.

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Temperature-Pressure Relationship

The change in pressure inside a scuba cylinder due to a change in temperature

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Amontons' Law in Scuba Diving

The effects of Amontons' Law on scuba cylinders.

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Dalton's Law of Partial Pressures

The total pressure of a gas mixture equals the sum of the partial pressures of each individual gas.

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Partial Pressure

The pressure exerted by a single gas in a mixture.

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Henry's Law

The amount of a gas dissolved in a liquid is directly proportional to its partial pressure above the liquid.

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Gas Tension

The pressure exerted by a dissolved gas in a liquid.

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Nitrox/Enriched Air

A mixture of breathing gas with a higher percentage of oxygen than atmospheric air.

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Absolute Pressure

The absolute pressure at a given depth, including atmospheric pressure.

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33 feet of Seawater (fsw)

The depth at which the absolute pressure is equal to two atmospheres (2.0 ATA).

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10 meters of Seawater (msw)

The depth at which the absolute pressure is equal to two atmospheres (2.0 ATA).

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Boyle's Law

A law that describes the relationship between the pressure and volume of a gas at a constant temperature. It states that the volume of a gas is inversely proportional to its pressure. This means that as the pressure increases, the volume decreases and vice versa. This law is important for understanding how gases behave under pressure, especially when diving.

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Atmospheres Absolute (ata)

The pressure of a gas at any depth is equal to the atmospheric pressure plus the pressure from the water above.

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Gas Compression

The volume of a gas decreases as the depth increases because of increasing pressure.

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Air Consumption and Depth

The amount of air you consume while diving increases with depth. This is because you need more molecules of air to fill your lungs at greater pressure.

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Dive Planning and Air Consumption

A way to calculate gas consumption at different depths. It takes into account the increase in air consumption due to pressure.

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Task Loading and Air Consumption

The amount of air you consume while diving, as a direct result of completing specific diving tasks or activities, such as underwater photography, setting up a dive site, or helping another diver.

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Physical Effort and Air Consumption

The amount of air you consume while diving, as a result of physical exertion during the dive.

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Study Notes

Physics of Diving - Part 1

  • The study covers the physics principles relevant to diving, including properties of water, pressure, gases, light, sound, and heat transfer.

States of Matter

  • Solid: A rigid substance resistant to forces. Example: ice
  • Liquid: A fluid with constant volume and nearly incompressible. Example: water
  • Gas: A flexible substance with molecules spaced further apart. Example: air

Density

  • Density is the compactness of a substance, often referred to as "heaviness"
  • Formula: Density = Mass/Volume (d = m/v)
  • Water is significantly denser than air, leading to noticeable differences in underwater experiences.

Water

  • Chemical formula: H₂O (two hydrogen atoms bonded to one oxygen atom)
  • Exists in all three states of matter, though "water" usually refers to the liquid state.
  • Properties: high surface tension, high boiling/freezing points, high heat capacity, and high density. Saltwater is denser than freshwater.

Pressure

  • Pressure is exerted by the weight of air, water, and other substances.
  • Formula: Pressure = Force/Area (P = F/A)
  • Types of diving pressure: atmospheric, hydrostatic, gauge, absolute, partial.

Atmospheric Pressure

  • The pressure exerted by the weight of the atmosphere.
  • At sea level, this pressure is 1 atmosphere, 14.7 psi, or 1013 mbar.
  • Pressure decreases with altitude.

Hydrostatic Pressure

  • The pressure exerted by the weight of the water.
  • Increases with depth at a rate of 1 atm (14.7 psi) for every 33 feet of seawater, and 34 feet for fresh water.

Gauge Pressure

  • Measures pressure relative to atmospheric pressure.
  • Zero at sea level.

Absolute Pressure

  • The total pressure exerted on a diver, combining atmospheric and hydrostatic pressure.

Partial Pressure

  • In gas mixtures, the pressure exerted by each gas is its partial pressure.
  • The total pressure is the sum of all the partial pressures. (Ptotal = PA + PB + PC ...)

Boyle's Law

  • At constant temperature, the volume of a gas is inversely proportional to its pressure. (P1V1 = P2V2).
  • As divers descend, the pressure increases, causing the air in their lungs to compress.
  • As divers ascend, the pressure decreases, causing air in their lungs to expand. This is a critical factor in dive planning and avoiding barotrauma.

Amontons' Law (Gay-Lussac's Law)

  • At a constant volume, the pressure of a gas is directly proportional to its absolute temperature. (P1/T1 = P2/T2).
  • Temperature changes in scuba cylinders affect their pressure.

Charles Law

  • At a constant pressure, the volume of a gas is directly proportional to its absolute temperature.
  • This law is less relevant to typical diving scenarios compared with the other gas laws.

Dalton's Law

  • The total pressure of a gas mixture is the sum of the partial pressures of its components.
  • Important for understanding gas mixtures, like air and Nitrox.

Henry's Law

  • The amount of gas dissolved in a liquid is proportional to its partial pressure in equilibrium with the liquid.
  • Explains the effects of pressure on gases dissolving in fluids (water), pertinent to decompression theory. Gases dissolve into liquids at a higher rate when pressure is greater. When pressure is lowered, the amount of gas in the liquid decreases.

Light

  • Light refracts (bends) when passing through water, which affects underwater vision.
  • Underwater light perception is different from above surface light; perceived distances, sizes, and colours are affected.
  • Turbidity in the water (cloudiness/ haziness) can affect the appearance of distance underwater

Underwater Sound

  • Water significantly affects the transmission of sound, making direction and distance estimations difficult.
  • Sound travels much faster in water compared to air

Heat and Water

  • Water conducts heat faster than air.
  • Water has a much higher heat capacity than air, meaning that it takes far more energy to change the temperature of water than it does the temperature of an equivalent weight of air.

Buoyancy

  • Archimedes' principle: An object immersed in a fluid experiences an upward buoyant force equal to the weight of the fluid displaced.
  • Specific gravity is the ratio of an object's density to that of water (or another reference fluid).
  • Buoyancy is crucial for divers to regulate their position in water. Divers constantly monitor and adjust their buoyancy and buoyancy compensation devices as needed.

Diving Considerations

  • Divers need to carefully consider the effect of these physics principles on their equipment and procedures. Proper training and preparation are crucial for safe and effective diving.

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Physics of Diving Part 1 PDF

Description

Explore the principles of physics that influence diving, including the properties of water, pressure, and states of matter. This quiz covers the essential concepts of density and the behavior of gases and liquids in the underwater environment, helping you understand the science behind diving.

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