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Physics Flashcards

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1
Q

What are the terms for the weight of water and the weight of the atmosphere over the water?

A

Water - Hydrostatic Pressure

Atmosphere - Atmospheric Pressure

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2
Q

What is the weight of the atmosphere at sea level?

A

14.7 psi

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3
Q

How do you calculate Hydrostatic Pressure?

A

Depth in Feet of Saltwater (fsw)
(fsw) x .445 = psig

Example: What is the hydrostatic pressure for 33 fsw?
33 x .445 = 14.68 (ROUND UP) = 15 psig

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4
Q

How do you calculate absolute pressure?

A

Depth to ATA:

D + 33 / 33 = ATA

Example: 60’ + 33 / 33 = 2.81 ata (round up from the hundredths)

PSIG to ATA:

psig + 14.7 / 14.7 = ATA

Example: 25 + 14.7 / 14.7 = 2.70 ata

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5
Q

What is the definition of absolute pressure (ata)?

A

The total pressure being exerted (i.e. gauge plus atmospheric pressure)

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6
Q

What gas law relates to buoyancy?

A

Archimedes Principle

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7
Q

What natural factors affect a diver’s buoyancy?

A
  1. Air in Lungs
  2. Bone Structure
  3. Body Fat
  4. Leanness
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8
Q

What are the factors that a diver can change to adjust buoyancy?

A
  1. Add or remove weight
  2. Put air in buoyancy compensator/life vest
  3. Put air in drysuit
  4. Put air in lungs
  5. Vary thickness of wetsuit
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9
Q

What equals the buoyant force?

A

Displaced liquid weight minus submerged body weight

Example: 
Object Displaces 20 lbs
Object Weighs    -10 lbs
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_
Positive                 10 lbs

Object Displaces 20 lbs
Object Weighs -30 lbs
___________________
Negative -10 lbs

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10
Q

What is the weight of fresh water and seawater?

A

Seawater Water: 64 lbs/cubic foot

Fresh Water: 62.4 lbs/cubic foot

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11
Q

What is the definition of Partial Pressure?

A

In a mixture of gases, each gas contributes to the total pressure of the mixture. This contribution is the partial pressure of the mixture. This contribution is the partial pressure. The partial pressure is the pressure the gas if the gas were in the same volume and temperature by itself.

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12
Q

What is the only gas the body can actually use?

A

Oxygen

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13
Q

What % of oxygen in air?

A

21%

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14
Q

What % of nitrogen in air?

A

79%

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15
Q

What type of gas is nitrogen and what are the properties?

A

Nitrogen is an inert gas, a gas that the body doesn’t metabolize, that dissolves into the body’s tissues. It is used to dilute O2. (basically a carrier for O2)

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16
Q

What is nitrogen narcosis?

A

A disorder resulting from anesthetic properties of nitrogen breathed under pressure (usually deeper than 100 fsw)

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17
Q

What produces Carbon Monoxide (CO)?

A

Incomplete Combustion of Fuels

18
Q

What produces Carbon Dioxide (CO2)?

A

By-product of respiration or metabolized O2 in the body

*when breathed at high pp or high concentrations, CO2 can be extremely toxic

19
Q

How does Boyle’s Law relate to diving?

A 
SPAM
S - squeezes
P - pulmonary over inflation syndromes (POIS)
A - air consumption 
M - minimum manifold pressure (MMP)
20
Q

What is minimum manifold pressure?

A

The supply pressure that will ensure that the gas supply will be delivered at a sufficient pressure to overcome the ambient seawater pressure and allow the equipment to supply the required amount of air to ventilate the rig being used.

21
Q

How does Charles/Gay Lussac’s Law relate to diving?

A

CAR
C - charging
A - air and stowage
R - recompression chamber ops

22
Q

What gas law is the law of partial pressure?

A

Dalton’s Law

23
Q

How do you figure the partial pressure (pp) of a gas at a given depth?

A

ATA x gas % = pp
* gas percentages must be expressed as their decimal equivalent for the equation (21% = .21)

Example: 
60' x 21%O2 = ppO2
2.81 x 21%O2 = ppO2
2.81 x .21 = ppO2
2.81 x .21 = .59 ppO2 at 60'
24
Q

How does Dalton’s Law relate to diving?

A

Gas toxicity at depth -

  1. O2 Toxicity
  2. Nitrogen Narcosis
25
Q

What gas law is the law of absorption?

A

Henry’s Law

26
Q

What factors affect gas absorption?

A
  1. Depth (deeper the depth, the higher the pp)
  2. Time at Depth (the longer you spend at that depth the more you will on-gas)
  3. Condition of your body to off-gas
27
Q

What are the variables for you bodies condition to off-gas?

A
  1. Temperature (lower the temp, the higher the solubility)
  2. Work Load (as the body cools it will cause vasoconstriction, the constriction of blood vessels, which increases blood pressure, and inhibit proper off-gassing
  3. Divers Physical Condition (fatty tissues hold more inert gas and take longer to off-gas than watery tissue)
28
Q

How much more soluble is inert gas in fat than in water?

A

5 times more soluble

29
Q

What is gas diffusion?

A

The process is the intermingling or mixing of gas molecules.

30
Q

How does gas diffusion relate to diving?

A

The amount that a gas will pass through a permeable membrane depends upon the partial pressure of the gas on both side of the membrane.
High pp of gas on one side of the membrane will DIFFUSE through the membrane to the low pp side until the pp is equalized.

The body is full of tissues that act as permeable membranes, hence we have on-gassing.

Increase Depth = Increase pp = on-gassing
Decrease Depth = Decrease pp = off-gassing

31
Q

What are the three types types of energy in diving?

A
  1. Light
  2. Mechanical (sound)
  3. Heat
32
Q

Objects under water appear to seem what?

A

Larger and Closer

33
Q

True or False

Light travels faster in air than water?

A

True

34
Q

Which type of water is denser, cold or warm?

A

Cold Water

35
Q

How many time faster does sound travel in water than air?

A

4 times faster

36
Q

What is a thermocline?

A

A cold or warm patch of water

37
Q

True or False

Air is a much better conductor of heat than water?

A

False

38
Q

At what water temperature will a diver lose heat faster than his body can replace it? (without a wetsuit)

A

70 Degrees F

39
Q

Body heat is lost how many times faster in water than in air?

A

25 times faster

40
Q

True or False

A diver who is chilled and can not work efficiently nor think clearly is more susceptible to DCS?

A

True

Physics and Charting (1 decks)

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