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Questions and Answers
What determines whether an object will float or sink in water?
What determines whether an object will float or sink in water?
When a box weighing -40 kg is subjected to a net positive force of 0.17 lbs, what can be concluded?
When a box weighing -40 kg is subjected to a net positive force of 0.17 lbs, what can be concluded?
How much lift is required to get a solid metal box weighing 200 lbs to the surface in saltwater?
How much lift is required to get a solid metal box weighing 200 lbs to the surface in saltwater?
What is the ultimate goal of an HPU scientific diver in terms of buoyancy?
What is the ultimate goal of an HPU scientific diver in terms of buoyancy?
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What should divers do if they find themselves sinking unexpectedly during a dive?
What should divers do if they find themselves sinking unexpectedly during a dive?
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When should a diver perform a weight check for proper weighting?
When should a diver perform a weight check for proper weighting?
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Why is it not advisable to simply add more weight while diving?
Why is it not advisable to simply add more weight while diving?
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What factor contributes to the variability of an individual's buoyancy underwater?
What factor contributes to the variability of an individual's buoyancy underwater?
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What does adding 1 ata to the pressure signify?
What does adding 1 ata to the pressure signify?
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If the pressure at a certain depth is 2 ata and the volume is 10 unit volumes, what is the volume at 1 ata?
If the pressure at a certain depth is 2 ata and the volume is 10 unit volumes, what is the volume at 1 ata?
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While descending to a depth where the pressure is 4 ata, how is the volume of gas affected?
While descending to a depth where the pressure is 4 ata, how is the volume of gas affected?
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What factor must be accounted for when planning a dive regarding air consumption?
What factor must be accounted for when planning a dive regarding air consumption?
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What happens to the buoyant force when a diver exhales air?
What happens to the buoyant force when a diver exhales air?
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Using Amontons' Law, what happens to the pressure if the temperature is doubled while volume remains constant?
Using Amontons' Law, what happens to the pressure if the temperature is doubled while volume remains constant?
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At a depth of 66'/20m, if air volume consumption is said to triple, what is the pressure at this depth?
At a depth of 66'/20m, if air volume consumption is said to triple, what is the pressure at this depth?
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How is specific gravity defined?
How is specific gravity defined?
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If an object displaces 1 ft³ of seawater, what is the upward buoyant force?
If an object displaces 1 ft³ of seawater, what is the upward buoyant force?
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To what does 'V1' represent in the reference to Boyle's Law?
To what does 'V1' represent in the reference to Boyle's Law?
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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?
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?
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What will happen to a 100 lbs sealed box that displaces 2 ft³ of water in saltwater?
What will happen to a 100 lbs sealed box that displaces 2 ft³ of water in saltwater?
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How much weight is equivalent to 1 liter of seawater?
How much weight is equivalent to 1 liter of seawater?
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Which of the following objects will definitely sink in saltwater?
Which of the following objects will definitely sink in saltwater?
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What must be done to make an object negatively buoyant?
What must be done to make an object negatively buoyant?
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What is the total upward force acting on a sealed box that weighs 40 kg and displaces 39 liters of water in saltwater?
What is the total upward force acting on a sealed box that weighs 40 kg and displaces 39 liters of water in saltwater?
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What is the total pressure exerted by a mixture of gases according to Dalton’s Law?
What is the total pressure exerted by a mixture of gases according to Dalton’s Law?
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For a diver breathing air at a depth of 33 feet, what is the partial pressure of Nitrogen?
For a diver breathing air at a depth of 33 feet, what is the partial pressure of Nitrogen?
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What percentage of Oxygen is used when calculating partial pressures for a diver breathing Enriched Air at 33 feet?
What percentage of Oxygen is used when calculating partial pressures for a diver breathing Enriched Air at 33 feet?
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Using Dalton’s Law, what is the total pressure exerted at a depth of 33 feet?
Using Dalton’s Law, what is the total pressure exerted at a depth of 33 feet?
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What occurs to the pressure of a scuba cylinder when it is moved from a shaded area to direct sunlight?
What occurs to the pressure of a scuba cylinder when it is moved from a shaded area to direct sunlight?
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According to Henry’s Law, what happens when gas is dissolved in a liquid?
According to Henry’s Law, what happens when gas is dissolved in a liquid?
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What does the term 'gas tension' refer to in the context of diving physiology?
What does the term 'gas tension' refer to in the context of diving physiology?
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When converting Fahrenheit to Rankine, what is the formula used?
When converting Fahrenheit to Rankine, what is the formula used?
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According to Amontons' Law, what happens to the pressure as the temperature in a scuba cylinder increases?
According to Amontons' Law, what happens to the pressure as the temperature in a scuba cylinder increases?
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When calculating the partial pressures contributed by each gas in a mixture, which component is often the smallest?
When calculating the partial pressures contributed by each gas in a mixture, which component is often the smallest?
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What would happen to the total pressure if a diver descended deeper than 33 feet?
What would happen to the total pressure if a diver descended deeper than 33 feet?
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If a scuba cylinder is filled and its temperature rises, what is the effect on the pressure?
If a scuba cylinder is filled and its temperature rises, what is the effect on the pressure?
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How much does the pressure in a scuba cylinder typically change for each degree Fahrenheit increase?
How much does the pressure in a scuba cylinder typically change for each degree Fahrenheit increase?
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What temperature scale should be used for calculations involving Amontons' Law?
What temperature scale should be used for calculations involving Amontons' Law?
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How do Charles' Law and Amontons' Law relate to one another?
How do Charles' Law and Amontons' Law relate to one another?
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If a scuba cylinder initially contains 3000 psi at 70°F, what is the resulting pressure when it warms to 95°F?
If a scuba cylinder initially contains 3000 psi at 70°F, what is the resulting pressure when it warms to 95°F?
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What characterizes a solid in the context of states of matter?
What characterizes a solid in the context of states of matter?
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Which principle explains the lifting needs in diving?
Which principle explains the lifting needs in diving?
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What is the weight of 1 cubic foot of seawater?
What is the weight of 1 cubic foot of seawater?
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Which equation represents the relationship between density, mass, and volume?
Which equation represents the relationship between density, mass, and volume?
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What does Boyle's Law describe concerning gases?
What does Boyle's Law describe concerning gases?
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What properties make water significantly different from air when diving?
What properties make water significantly different from air when diving?
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How does Dalton's Law apply to diving?
How does Dalton's Law apply to diving?
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What is a unique property of a liquid state of matter?
What is a unique property of a liquid state of matter?
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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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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.
