Diver Physics

Question 1

reasons not to recompress a victim of decompression illness in the water is:

Answer 1

Recompression takes a long time, so there may not be an adequate air supply.

It may be difficult to administer oxygen at depth.
The diver may still be on-gassing nitrogen, worsening the condition.

Another diver acting as an attendant would also be at risk.

Question 2

What is the primary consideration in the first aid of a blue-ringed octopus bite?

Answer 2

DRABC (Danger, Response, Airway, Breathing, Circulation); Seek medical aid; apply a pressure immobilization bandage; maintain EAR (Ensure Airway and Breathing) until help arrives.

Question 3

The recommended first aid procedure for stonefish envenomation

Answer 3

DRABCD (Danger, Response, Airway, Breathing, Circulation, Defibrillation if necessary)
Immerse the puncture site in water as hot as the patient can stand to help alleviate pain.
Seek immediate medical aid.

Question 4

What is the recommended depth limit for recreational scuba diving?

Answer 4

A: The recommended depth limit for recreational scuba diving is 40 meters (130 feet).

Question 5

Q: What is the most common gas used for breathing in scuba diving?

Answer 5

compressed air.

Question 6

What is the term for the feeling of confusion and euphoria experienced by divers at greater depths?

Answer 6

The term for this feeling is nitrogen narcosis.

Question 7

What are the signs and symptoms of oxygen toxicity?

Answer 7

Signs and symptoms of oxygen toxicity can include seizures, visual disturbances, and difficulty breathing.

Question 8

What is the purpose of a surface marker buoy (SMB)?

Answer 8

A surface marker buoy is used to indicate the diver’s position on the surface and signal to boats that divers are below.

Question 9

What is the maximum allowable surface interval between repetitive dives?

Answer 9

24 hours.

Question 10

What is the purpose of a dive computer?

Answer 10

A dive computer is used to monitor and calculate the diver’s depth, bottom time, and decompression requirements during a dive.

Question 11

What is the recommended ascent rate for scuba divers?

Answer 11

The recommended ascent rate for scuba divers is 9-18 meters per minute (30-60 feet per minute).

Question 12

What is the correct procedure for equalizing the ears while descending?

Answer 12

The correct procedure is to gently pinch the nostrils and blow gently against a closed airway to equalize the pressure.

Question 13

What is the recommended interval between diving and flying in an airplane?

Answer 13

The recommended interval between diving and flying is typically 12-24 hours, depending on the depth and duration of the dives.

Question 14

What is the purpose of a dive buddy system in scuba diving?

Answer 14

The dive buddy system is a safety measure where each diver is paired with another diver to closely monitor and assist each other throughout the dive.

Question 15

What does the acronym BCD stand for in scuba diving?

Answer 15

BCD stands for Buoyancy Control Device, which is a piece of equipment that allows divers to control their buoyancy underwater.

Question 16

What is the term for the process of breathing in and out of a regulator to prevent the buildup of carbon dioxide?

Answer 16

The term for this process is “regulator clearing” or “purging.”

Question 17

What is the recommended method for ascending to the surface in case of an emergency while scuba diving?

Answer 17

The recommended method is to make a controlled, slow ascent while continuously exhaling and making safety stops as required.

Question 18

What is the purpose of a safety stop in scuba diving?

Answer 18

A safety stop is a brief period of time spent at a shallow depth (typically around 3-5 meters or 10-15 feet) to allow for off-gassing of nitrogen and reduce the risk of decompression sickness.

Question 19

What is the maximum depth limit for recreational diving without decompression stops?

Answer 19

40m

Question 20

What are the signs and symptoms of nitrogen narcosis?

Answer 20

euphoria, impaired judgment, slowed reaction time, and loss of coordination.

Question 21

What is the recommended time interval between scuba diving and donating blood?

Answer 21

The recommended time interval between scuba diving and donating blood is typically 24 hours or longer to ensure nitrogen has sufficiently off-gassed from the body.

Question 22

What is the purpose of a dive flag or float?

Answer 22

A dive flag or float is used to mark the location of divers in the water and indicate to surface vessels that divers are below.

Question 23

What is the term for the condition when a diver holds their breath during ascent?

Answer 23

“lung barotrauma.”

Question 24

What is the term for the process of removing water from a flooded scuba mask while underwater?

Answer 24

clearing mask

Question 25

1. Describe the effect that the following has on gas molecules in a sealed container. (15 marks)
   (a) An increase in temperature

Answer 25

Charles’ Law: Molecules increase energy state, resulting in more impacts on the side of the container. Increase in volume if flexible container; increase in pressure if rigid container

Question 26

1. Describe the effect that the following has on gas molecules in a sealed container.
   (b) A decrease in volume

Answer 26

Boyles’ Law: Molecules strike side of the container more often. Results in an increase in pressure and an increase in temperature.

Question 27

1. Describe the effect that the following has on gas molecules in a sealed container.
   An increase in pressure

Answer 27

Boyles’ Law & Charles’ Law: Decrease in volume and an increase in temperature.

Question 28

explain Atmospheric Pressure

Answer 28

The pressure resulting from the weight of atmospheric gases above an object.

Question 29

Hydrostatic Pressure

Answer 29

The pressure resulting from the weight of liquid above an object.

Question 30

Absolute Pressure

Answer 30

The sum of the atmospheric (bar) and hydrostatic pressures exerted on a submerged object resulting from the weight of the atmosphere and the liquid above the object.

Question 31

Gauge Pressure

Answer 31

Is the difference between absolute pressure and any specific pressure being measured. For diving, gauge pressure is usually the same as hydrostatic pressure, and is used to measure depth.

Question 32

describe buoyancy

Answer 32

An object immersed in a liquid will displace an amount of liquid equal to the volume of the immersed object, and any object wholly or partially immersed in a fluid is buoyed up by a force equal to the weight of the fluid displaced.

Question 33

4. Why do objects appear closer and larger underwater?

Answer 33

Because when a diver wears a mask, they introduce three points of refraction for light, and the eye is unable to adjust for the refraction caused by the glass

Question 34

5. What effect does water have on sound, and how does this affect us?

Answer 34

Sound travels 4-5 times faster in water than in air, and because humans detect the direction sound comes from in air by using the time lag between the sound reaching each ear, we are unable to detect this lag when the sound is travelling faster.
Also, sound is transmitted through water directly into our skull/ears, which also makes this harder.

Question 35

6. Describe Boyle’s Law?

Answer 35

Boyles Law: Pressure/Volume inverse relationship.

Question 36

7. Using the Ideal Gas Law P1 = P2, calculate the final pressure in a 1500 litre cylinder.
   T1 T2

Question 37

8. Using the Ideal Gas Law P1 x V1= P2 x V2, calculate the final P in a 1500 litre cylinder.
   T1 T2

Question 37

At what depth in salt water would a diver be subject to a pressure of 4 atmospheres absolute?

Answer 37

30 m

surface = 1
10 = 2
20=3
30 = 4

Question 37

the amount of dissolved nitrogen in the blood

Answer 37

increases with increased depth

Question 37

A diver has difficulty locating sound underwater because:

Answer 37

the speed of sound underwater in increased

Question 37

The partial pressure of oxygen in air at 40 m is:
a) 0.5 ata
b) 0.8 ata
c) 1.0 ata
d) 1.6 ata

Answer 37

air is 21% in air - at 40m, = +4 ATA, plus surface ATA = 5 ATA

-0.21 x 5 ATA = 0.8 ATA

Question 38

When light travels through water, the colour to be absorbed first is:
a) Yellow
b) Blue
c) Red
d) Orange

Answer 38

red

longer wavelengths are absorbed first