Q Flashcards
(161 cards)
1
Q
What is buoyancy?
A
The force that supports an object in a liquid, allowing it to float, sink, or remain neutrally buoyant.
2
Q
What is neutral buoyancy?
A
When an object neither sinks nor floats, achieved by balancing weight and buoyancy (e.g., using a BCD).
3
Q
How does pressure increase with depth in water?
A
Pressure increases by 1 atmosphere (ata) for every 10 meters/33 feet of seawater.
4
Q
What is the absolute pressure at 10 meters/33 feet in seawater?
A
2 ata (1 ata from air + 1 ata from 10 meters of water).
5
Q
How does Boyle’s Law apply to diving?
A
As pressure increases with depth, gas volume decreases; as pressure decreases, gas volume increases.
6
Q
Why must divers ascend slowly?
A
To allow expanding gases in the lungs to escape safely, preventing lung overexpansion injuries.
7
Q
What is the relationship between pressure and gas density?
A
As pressure increases with depth, gas density increases, making air thicker to breathe.
8
Q
What is a squeeze in diving?
A
Pain or discomfort caused by pressure imbalance in air spaces (e.g., ears, sinuses) during descent.
9
Q
How do you equalize your ears during descent?
A
Pinch your nose and gently blow (Valsalva maneuver) or swallow (Toynbee maneuver) to open Eustachian tubes.
10
Q
What happens to colors underwater?
A
Colors are absorbed by water; red disappears first, followed by orange, yellow, etc., with increasing depth.
11
Q
Why do objects appear larger underwater?
A
Light refracts in water, magnifying objects by about one-third.
12
Q
How does water affect sound underwater?
A
Sound travels four times faster in water than in air, making it harder to locate the source.
13
Q
What is the formula for calculating absolute pressure in diving?
A
Absolute pressure (ata) = depth (meters) / 10 + 1 (or depth (feet) / 33 + 1).
14
Q
What is the partial pressure of oxygen at sea level (1 ata)?
A
Approximately 0.21 ata (21% of 1 ata).
15
Q
What is the volume of a balloon at 20 meters if it was 10 liters at the surface?
A
3.33 liters (Boyle’s Law: 10 liters / (20m / 10 + 1) = 10 / 3).
16
Q
What is Dalton’s Law in diving?
A
The total pressure of a gas mixture is the sum of the partial pressures of its component gases.
17
Q
Why do divers feel less weight underwater?
A
Buoyancy counteracts gravity, making objects feel lighter.
18
Q
What is Archimedes’ Principle?
A
An object in a fluid is buoyed up by a force equal to the weight of the fluid displaced.
19
Q
How does temperature affect diving?
A
Water conducts heat 20 times faster than air, increasing the risk of hypothermia.
20
Q
What is decompression sickness (DCS)?
A
A condition caused by nitrogen bubbles forming in the body due to rapid ascent.
21
Q
What are symptoms of decompression sickness?
A
Joint pain, fatigue, dizziness, rash, or neurological issues (e.g., numbness, paralysis).
22
Q
How can divers prevent decompression sickness?
A
Ascend slowly, perform safety stops, and follow dive tables or computers.
23
Q
What is a safety stop, and when is it performed?
A
A 3–5 minute pause at 5 meters/15 feet to allow nitrogen off-gassing.
24
Q
What is nitrogen narcosis?
A
Impaired mental function due to nitrogen under pressure, typically below 30 meters/100 feet.
25
What is the “martini rule” for nitrogen narcosis?
Every 10 meters/33 feet below 20 meters feels like one martini (e.g., 30m = 1 martini).
26
What is an arterial gas embolism (AGE)?
Gas bubbles entering the bloodstream due to lung overexpansion, potentially causing stroke-like symptoms.
27
What causes lung overexpansion injuries?
Holding your breath during ascent, causing air in the lungs to expand.
28
How do you prevent lung overexpansion injuries?
Breathe continuously and ascend slowly (no faster than 18m/60ft per minute).
29
What is oxygen toxicity in diving?
Excessive oxygen partial pressure (usually >1.4 ata) causing convulsions or other symptoms.
30
What is the maximum depth for recreational diving on air to avoid oxygen toxicity?
56 meters/184 feet (where oxygen partial pressure reaches 1.4 ata).
31
What is a reverse squeeze?
Pain in air spaces (e.g., ears) during ascent due to trapped gas; solved by descending slightly.
32
Why do divers get dehydrated?
Breathing dry tank air and immersion diuresis (pressure-induced urination) increase fluid loss.
33
What is the effect of cold water on divers?
Increases risk of hypothermia and reduces dexterity, affecting equipment handling.
34
What is the purpose of a dive computer?
Tracks depth, time, and nitrogen absorption to prevent decompression sickness.
35
What is the no-decompression limit (NDL)?
The maximum time a diver can stay at a depth without requiring decompression stops.
36
What happens if you exceed the no-decompression limit?
You may need decompression stops to safely off-gas nitrogen, or risk DCS.
37
What is a repetitive dive?
A dive conducted within 6–24 hours of a previous dive, with residual nitrogen in the body.
38
How does altitude affect diving?
Lower atmospheric pressure at altitude reduces safe dive times; use altitude dive tables.
39
What is the role of the diaphragm in breathing?
The muscle that contracts to draw air into the lungs; divers must breathe deeply using it.
40
What is a BCD (Buoyancy Control Device)?
An inflatable vest used to control buoyancy by adding or releasing air.
41
What are the main components of a scuba regulator?
* First stage (attaches to tank) * Second stage (mouthpiece) * Alternate air source * Gauges
42
What does the SPG (submersible pressure gauge) do?
Displays the remaining air pressure in the tank.
43
What is the purpose of a dive mask?
Creates an air space to allow clear vision underwater and protects the eyes.
44
How do you clear a flooded mask underwater?
Tilt head back, press the top of the mask, and exhale through your nose.
45
What is the role of fins in diving?
Increase swimming efficiency and reduce energy use; types include open-heel and full-foot.
46
What is a snorkel used for in scuba diving?
Allows breathing at the surface without using tank air, conserving gas.
47
What is a weight system?
Lead weights used to counteract buoyancy, allowing divers to sink.
48
How do you check your weight system before a dive?
Ensure weights are secure and quick-release mechanisms work properly.
49
What is a dive computer, and why is it important?
Tracks depth, time, and nitrogen levels to ensure safe dive profiles.
50
What is the purpose of a tank boot?
Protects the tank base and prevents it from rolling on a boat.
51
What is a low-pressure inflator hose?
Connects the BCD to the regulator to add air for buoyancy control.
52
Why do divers wear exposure suits?
To protect against cold, sunburn, abrasions, and marine life stings.
53
What is the difference between a wetsuit and a drysuit?
Wetsuits insulate with a thin layer of water; drysuits keep you dry and insulate with air.
54
What is a dive knife used for?
To cut fishing lines, nets, or other entanglements, not as a weapon.
55
How often should scuba equipment be serviced?
Annually or per manufacturer guidelines, plus visual inspections before dives.
56
What is an O-ring in scuba equipment?
A rubber seal in the tank valve or regulator to prevent air leaks.
57
What should you do if your regulator free-flows?
Breathe lightly from it while ascending; use alternate air source if needed.
58
What is a surface marker buoy (SMB)?
An inflatable device to signal your position to the boat or surface.
59
How do you perform a pre-dive equipment check (BWRAF)?
* Buoyancy * Weights * Releases * Air * Final OK—check BCD, weights, quick releases, air supply, and gear.
60
What is the buddy system in diving?
Diving with a partner for safety, mutual assistance, and emergency response.
61
What is the most important rule in scuba diving?
Never hold your breath; breathe continuously to avoid lung injuries.
62
What is the recommended ascent rate for divers?
No faster than 18 meters/60 feet per minute (or follow dive computer).
63
How do you perform a controlled emergency swimming ascent (CESA)?
Swim to the surface while exhaling continuously, keeping the regulator in your mouth.
64
What is the hand signal for 'OK'?
Form a circle with thumb and index finger, other fingers extended.
65
What is the hand signal for 'Problem' or 'Something’s wrong'?
Hand flat, palm down, tilting side to side.
66
How do you share air with a buddy?
Offer your alternate air source (octopus) or use their alternate air source.
67
What should you do if you run out of air?
Signal your buddy, share air, and ascend together safely.
68
What is the purpose of a pre-dive safety check?
To ensure all equipment is functioning and both divers are ready.
69
What is a giant stride entry?
A method of entering deep water by stepping off a platform with a large step, regulator in mouth.
70
How do you perform a back roll entry?
Sit on the edge of a boat, hold your mask and regulator, and roll backward into the water.
71
What is the purpose of a dive plan?
To outline depth, time, air management, and emergency procedures for a safe dive.
72
What is the minimum air pressure to surface safely?
50 bar/500 psi to ensure enough air for ascent and safety stop.
73
How do you clear a regulator underwater?
Exhale sharply or press the purge button to remove water.
74
What is a buddy check, and when is it done?
A pre-dive inspection of each other’s gear, done before entering the water.
75
What should you do if you get separated from your buddy?
Search for one minute (360-degree turn), then ascend to the surface.
76
What is the hand signal for 'Low on air'?
Hand flat across the throat or pointing to the SPG.
77
How do you control buoyancy during a dive?
Adjust air in the BCD and use proper breathing (inhale to rise, exhale to descend).
78
What is a safety stop, and why is it important?
A pause at 5 meters/15 feet for 3–5 minutes to off-gas nitrogen and reduce DCS risk.
79
What should you do if you feel a reverse block in your ears?
Descend slightly to relieve pressure, then ascend slowly.
80
What is the hand signal for 'Ascend'?
Thumb pointing upward.
81
What is the hand signal for 'Descend'?
Thumb pointing downward.
82
How do you perform a weight belt removal underwater?
Unbuckle the belt, hold it away from your body, and drop it if necessary.
83
What is the purpose of a dive flag?
Alerts boats to divers in the area to avoid collisions.
84
What should you do if caught in a current?
Swim across the current to shore or signal for help; don’t fight it directly.
85
What is the procedure for an out-of-air emergency?
Signal buddy, share air, ascend together slowly with a safety stop if possible.
86
How do you prevent mask fogging?
Apply defog solution (e.g., spit or commercial spray) before the dive.
87
What is the hand signal for 'Stop'?
Hand flat, palm facing forward.
88
What should you do if you see marine life acting aggressively?
Stay calm, maintain distance, and slowly back away without sudden movements.
89
How do you log a dive?
Record depth, time, location, air used, and notable observations in a dive logbook.
90
Why should divers avoid touching coral reefs?
Touching can damage or kill coral, disrupting marine ecosystems.
91
What is the role of a responsible diver in marine conservation?
Minimize impact, avoid disturbing wildlife, and collect debris if safe.
92
What is neutral buoyancy’s role in environmental protection?
Prevents accidental contact with reefs or marine life, reducing damage.
93
What should you do if you see marine debris?
Collect it if safe and within your training, or report it to authorities.
94
Why is sunscreen harmful to coral reefs?
Chemicals like oxybenzone can bleach and damage coral.
95
What is the purpose of marine protected areas (MPAs)?
To conserve marine ecosystems by limiting fishing, diving, or other activities.
96
How can divers avoid disturbing marine life?
Maintain distance, avoid chasing animals, and move slowly to prevent stress.
97
What is coral bleaching?
When corals expel algae due to stress (e.g., warm water), causing them to turn white and potentially die.
98
Why should divers avoid feeding marine animals?
Feeding disrupts natural behaviors and can harm their health.
99
What is the PADI AWARE program?
An initiative to promote ocean conservation through education and action.
100
How does pressure change with depth in seawater?
Increases by 1 ata every 10 meters.
101
According to Boyle’s Law, what happens to the volume of a gas as a diver descends to 20 meters?
Volume is reduced to one-third.
102
Why do objects appear larger underwater?
Water refracts light.
103
What is the absolute pressure at 30 meters in seawater?
4 ata.
104
How does sound travel underwater compared to air?
Four times faster than in air.
105
What is buoyancy?
The force that supports objects in a liquid.
106
What is neutral buoyancy?
Neither sinking nor floating.
107
What causes a squeeze during descent?
Pressure imbalance in air spaces.
108
How do you equalize your ears during descent?
Pinch nose and blow gently.
109
Which color disappears first underwater?
Red.
110
What is the partial pressure of oxygen at sea level (1 ata)?
0.21 ata.
111
What is Dalton’s Law in diving?
Total pressure is the sum of partial pressures.
112
What is the volume of a 12-liter balloon at 10 meters?
6 liters.
113
Why do divers feel less weight underwater?
Buoyancy counteracts gravity.
114
What is Archimedes’ Principle?
Objects are buoyed by the weight of displaced fluid.
115
How does water affect heat loss?
Conducts heat 20 times faster than air.
116
What happens to gas density at 40 meters?
Increases.
117
What is the absolute pressure at the surface?
1 ata.
118
Why is slow ascent important?
Avoids lung overexpansion.
119
What is the effect of refraction on vision underwater?
Objects appear closer and larger.
120
What is the primary cause of decompression sickness (DCS)?
Nitrogen bubbles forming in the body.
121
What is the recommended action to prevent lung overexpansion injuries?
Breathe continuously.
122
At what depth does nitrogen narcosis typically become noticeable?
30 meters/100 feet.
123
What is the purpose of a safety stop?
To allow nitrogen off-gassing.
124
What is a symptom of oxygen toxicity?
Convulsions.
125
What is nitrogen narcosis often compared to?
Feeling drunk.
126
What is the 'martini rule' for nitrogen narcosis?
1 martini per 10 meters below 20 meters.
127
What causes an arterial gas embolism (AGE)?
Lung overexpansion.
128
What is the maximum recreational dive depth on air to avoid oxygen toxicity?
56 meters.
129
What is a reverse squeeze?
Pain during ascent due to trapped gas.
130
Why do divers get dehydrated?
Breathing dry tank air and immersion diuresis.
131
What is the purpose of a dive computer?
Tracks depth, time, and nitrogen levels.
132
What is the no-decompression limit (NDL)?
Maximum time at a depth without decompression stops.
133
What happens if you exceed the no-decompression limit?
Need decompression stops.
134
What is a repetitive dive?
A dive within 6–24 hours of another dive.
135
How does altitude affect diving?
Reduces safe dive time.
136
What is a symptom of decompression sickness?
Joint pain or dizziness.
137
What is the role of the diaphragm in diving?
Draws air into lungs.
138
What increases the risk of hypothermia in diving?
Cold water and heat loss.
139
What is the effect of immersion diuresis?
Increased urination.
140
What is the primary function of a BCD?
Controls buoyancy.
141
What should you do if your mask floods underwater?
Exhale through your nose while pressing the mask.
142
What does the SPG measure?
Air pressure in the tank.
143
What is the purpose of an alternate air source?
Provides backup air in case of primary source failure.
144
What should you do if your mask floods?
Exhale through your nose while pressing the mask
## Footnote
This clears water from the mask.
145
What does the SPG measure?
Air pressure in the tank
## Footnote
The SPG shows remaining air in the scuba tank.
146
What is the purpose of an alternate air source?
Shares air with a buddy
## Footnote
The alternate air source is for emergency air sharing.
147
Why do divers wear weight systems?
Counteract buoyancy
## Footnote
Weights help divers descend by overcoming buoyancy.
148
What is the purpose of a dive mask?
Creates an air space for vision
## Footnote
Masks allow clear underwater vision.
149
What are fins used for in diving?
Increase swimming efficiency
## Footnote
Fins reduce energy use while swimming.
150
What is a snorkel’s purpose in scuba diving?
Conserves tank air at the surface
## Footnote
Snorkels allow surface breathing without using tank air.
151
How often should scuba equipment be serviced?
Annually or per manufacturer guidelines
## Footnote
Regular servicing ensures safety.
152
What is a dive knife used for?
Cutting entanglements
## Footnote
Dive knives cut lines or nets, not for weapons.
153
What is a low-pressure inflator hose?
Connects BCD to regulator
## Footnote
It adds air to the BCD for buoyancy control.
154
What should you do if your regulator free-flows?
Breathe lightly and ascend
## Footnote
Use the alternate air source if needed.
155
What is a surface marker buoy (SMB)?
Signals position to boats
## Footnote
SMBs mark a diver’s location at the surface.
156
What does BWRAF stand for in a pre-dive check?
Buoyancy, Weights, Releases, Air, Final OK
## Footnote
BWRAF ensures equipment is ready.
157
What is the purpose of an O-ring in scuba gear?
Prevents air leaks
## Footnote
O-rings seal tank valves and regulators.
158
What is the difference between a wetsuit and a drysuit?
Drysuits keep you dry
## Footnote
Wetsuits insulate with water; drysuits use air.
159
What is a tank boot’s purpose?
Protects tank base
## Footnote
Tank boots prevent rolling and damage.
160
How do you check a weight system before a dive?
Ensure quick-release works
## Footnote
This ensures weights can be dropped in an emergency.
161
What is the purpose of an exposure suit?
Protects against cold and stings
## Footnote
Exposure suits are essential for thermal protection.
