Dive master exam questions and answers with complete
solution
Why does water absorb more heat than air?
- it is denser
- it forms weaker bonds
What takes away heat from the body... times faster than air
20
Refraction magnifies objects underwater by a ratio of ...
4:3
objects appear ... % closer and ... % larger underwater
25 %, 33%
Light changes... as it passes through water
speed, causing it to change direction slightly
What is visual reversal?
in very clear water objects appear further away due to the particles in the water that
resembles haze over great distance
Sound travels slightly more than ... times faster in water than air
4
What determines how well sound travels through a substance?
Elasticity- water has a higher elasticity than air so travels faster
what is absolute absolute pressure
the total pressure
what is ambient pressure
the surrounding pressure
for every ... metres, the pressure increases by ... (plus one for the surface)
10, 1
for every ... meters in freshwater, the pressure increases by 1
10.3
Double the surface pressure=
half the volume
at a depth of 20 metres, what would the pressure and volume be?
Pressure = 3 bar and volume = 1/3 full
Double pressure..
double the density (or half pressure = half the density)
if we were diving 40 meters, the cylinder would only last ... of the time at the
surface
1/5
What is the amount of buoyancy based off?
how much fluid the object displaces compared to its weight
how do you increase buoyancy?
reducing weight and increasing displacement
how do we calculate partial pressure?
multiply the percentage of the gas by the pressure dpeth
what is the partial pressure of oxygen set at?
, 1.4 bar for recreational diving
what is saturation
the pressure of the dissolved gas will equalize with the pressure of the gas in contact
with the liquid
What is supersaturation?
when pressure decreases the dissolved gas begins to come out of the solution
what is dead air space and why is it a concern?
gas that remains in ur sinuses and doesnt participate in gas exchange. When you
breathe shallow and rapid the proportion of dead air space increases leading to
increased carbon dioxide levels
Why is carbon monoxide poisonous?
because it binds with haemoglobin (which oxygen normally binds too), reducing the
ability to carry adeqaute oxygen around the body
what are the two types of oxygen toxicity?
1. central nervous system toxicity
2. pulmonary toxicity
what is the acronym used for CNS toxicity?
Ventid
visual disturbance
ears ringing
nausea
twitching
irritability
dizziness
why does gas narcosis occur?
results from has blocking/delaying the transmission of signals within the nervous system
which type of decompression sickness is the most life threatening?
type 2 DCS
What are the signs of heat stroke?
Perspiration stops and the persons skin is hot and flush, pulse is rapid and strong
What are signs of hypothermia
shivering stops and capillaries dilate, returning blood to the skin. The person feels warm
but the core temp is dropping rapidly
what do burst disc do?
release pressure by being made of thin metal that bursts well below the cylinders failure
pressure
what does a hydrostatic test do?
compares the weight and displacement of a cylinder before and after filling it to test
pressure
After how many half times do we consider the compartment saturated with the
surrounding tissue?
six
fast compartments have ... M values
high
slow compartments have ... M values
slow
solution
Why does water absorb more heat than air?
- it is denser
- it forms weaker bonds
What takes away heat from the body... times faster than air
20
Refraction magnifies objects underwater by a ratio of ...
4:3
objects appear ... % closer and ... % larger underwater
25 %, 33%
Light changes... as it passes through water
speed, causing it to change direction slightly
What is visual reversal?
in very clear water objects appear further away due to the particles in the water that
resembles haze over great distance
Sound travels slightly more than ... times faster in water than air
4
What determines how well sound travels through a substance?
Elasticity- water has a higher elasticity than air so travels faster
what is absolute absolute pressure
the total pressure
what is ambient pressure
the surrounding pressure
for every ... metres, the pressure increases by ... (plus one for the surface)
10, 1
for every ... meters in freshwater, the pressure increases by 1
10.3
Double the surface pressure=
half the volume
at a depth of 20 metres, what would the pressure and volume be?
Pressure = 3 bar and volume = 1/3 full
Double pressure..
double the density (or half pressure = half the density)
if we were diving 40 meters, the cylinder would only last ... of the time at the
surface
1/5
What is the amount of buoyancy based off?
how much fluid the object displaces compared to its weight
how do you increase buoyancy?
reducing weight and increasing displacement
how do we calculate partial pressure?
multiply the percentage of the gas by the pressure dpeth
what is the partial pressure of oxygen set at?
, 1.4 bar for recreational diving
what is saturation
the pressure of the dissolved gas will equalize with the pressure of the gas in contact
with the liquid
What is supersaturation?
when pressure decreases the dissolved gas begins to come out of the solution
what is dead air space and why is it a concern?
gas that remains in ur sinuses and doesnt participate in gas exchange. When you
breathe shallow and rapid the proportion of dead air space increases leading to
increased carbon dioxide levels
Why is carbon monoxide poisonous?
because it binds with haemoglobin (which oxygen normally binds too), reducing the
ability to carry adeqaute oxygen around the body
what are the two types of oxygen toxicity?
1. central nervous system toxicity
2. pulmonary toxicity
what is the acronym used for CNS toxicity?
Ventid
visual disturbance
ears ringing
nausea
twitching
irritability
dizziness
why does gas narcosis occur?
results from has blocking/delaying the transmission of signals within the nervous system
which type of decompression sickness is the most life threatening?
type 2 DCS
What are the signs of heat stroke?
Perspiration stops and the persons skin is hot and flush, pulse is rapid and strong
What are signs of hypothermia
shivering stops and capillaries dilate, returning blood to the skin. The person feels warm
but the core temp is dropping rapidly
what do burst disc do?
release pressure by being made of thin metal that bursts well below the cylinders failure
pressure
what does a hydrostatic test do?
compares the weight and displacement of a cylinder before and after filling it to test
pressure
After how many half times do we consider the compartment saturated with the
surrounding tissue?
six
fast compartments have ... M values
high
slow compartments have ... M values
slow
