# Diving Physics

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1. Pounds per Square Inch (PSI) per foot in SEAWATER
.445 psi per foot
2. Pounds per Square Inch (PSI) per foot in FRESH WATER
.432 psi per foot
3. Atmospheric pressure at SEA LEVEL
14.7 PSI or 1 Atmosphere absolute
4. Specific Gravity of PURE WATER
1.0
5. If an object sinks in water the object's buoyancy is...
NEGATIVE
6. If an object floats in water the object's buoyancy is...
POSITIVE
7. If an object neither sinks nor floats in water the object's buoyancy is...
NEUTRAL
8. "An object wholly or partly immersed in a fluid is BUOYED up by a force equal to the weight of the fluid displaced by the object." What is this principle called?
Archimedes Principle
9. How much does one cubic foot of SEAWATER weigh?
64 pounds
10. How much does one cubic foot of FRESH WATER weigh
62.4 pounds
11. If an object is NEUTRALLY buoyant in FRESH WATER the object will __________ in SEAWATER
FLOAT or has POSITIVE BUOYANCY (this is due to the disolved salts in seawater making the specific gravity of SEATER approximately 1.03)
12. The volume of a gas is inversely proportional to the absolute pressure. This means...

If pressure goes up, the volume of the gas decreases (gets smaller) while density increases.

If pressure goes down the volume of the gas increases (gets larger) while the density decreases.

What is the name of this law?
BOYLES LAW
13. What gas law uses this equation?

P1 x V1 = P2 x V2

works as:

P1 x V1 / P2 = V2
or
P1 x V1 / V2 = P2
BOYLES LAW
14. If an object is NEUTERALLY buoyant in SEAWATER it will ___________ in FRESH WATER
SINK or be NEGATIVELY BUOYANT (this is due to the disolved slats in seawater)
15. A SCUBA cylinder will change approximately how many PSI per 1 degree of temprature change Farenheit?
5 psi

• Example: 3000 psi tank taken from 80 degrees on land to 40 degrees in water how what will the tank pressure be in the water
• 80 - 40 = 40 degree total change
• 40 x 5psi per degree = 200 psi change
• 3000 psi - 200 psi = 2800 psi in the water
16. What is the fomula for Boyles Law?
• P1 x V1 = P2 x V2
• works as:
• P1 x V1 / P2 = V2
• or
• P1 x V1 / V2 = P2
17. What gas law uses this fomula?

P1 x V1 = P2 x V2
T1 = T2
Charles Law
18. Add what number to degrees Farenheit to determine Rankine?
460

Example 80 F + 460 = 540 degree Rankine
19. What is the absolute pressure for a depth of 87 feet in SEAWATER in PSI
53.41 psi

(87 feet x .445 psi per foor of depth +14.7 surface atmosphere)
20. What is the GAUGE pressure in PSI for a depth of 106 feet in SEAWATER
47.17 PSI

106 feet x .445
21. What is the absolute pressure in ATMOSPHERES for a depth of 134 feet in SEAWATER
5.06

134 feet / 33 feet per atmosphere + 1 atmosphere for surface pressure
22. What is the GAUGE pressure in ATMOSPHERES for 93 feet in FRESHWATER
2.73

93 feet / 34 feet per atmosphere
23. How many feet of depth equals one atmosphere in SEAWATER
33 feet

for each 33 feet of depth pressure increases by 1 atmosphere
24. How many feet of depth equals one atmosphere in FRESH WATER
34 feet

Every 34 feet of depth in fresh water pressure increases by one atmosphere
25. A scuba cylinder is pressurized to 3000 psi at 80 degree Farenheit. What will the APPROXIMATE pressure of the tank be in PSI if the tank is taken into 40 degree Farenheit water.
2800 psi

1 degree of teprature change equals a 5psi change in the cylinder

80 - 40 = 40 degrees change in temprature. 40 x 5 = 200 psi change 3000psi - 200 psi = 2800 psi
26. A scuba cylinder is pressurized to 3000 psi at 80 degree Farenheit. What will the EXACT pressure of the tank be in PSI if the tank is taken into 40 degree Farenheit water.
2777PSI

• P1=3000 psi
• V1=80 cubic foot tank
• T1= 540 (80+460 to equal rankine)
• P2= UNKNOWN
• V2=80 cubic foot tank
• T2= 500 (40+460 to equal rankine) The math is: 3000 x 500 / 540 we can delete the volume becuase it does not change
27. A balloon filled with 1 cubic foot of air at room temprature. What will happen to the volume of the air in the balloon if the balloon is placed into a freezer?
The volume will decrease.

A balloon is a flexible container. the change in temprature will cause the volume to chage becuase of the flexible container.

CHARLES LAW
28. A scuba cyliner is filled to capacity at room temprature. What will happen if the tank is taken on an ice dive in near freezing water. Will tank's volume change? Will the tank's pressure change?
The tank's volume will not change becuase it is not a flexible container.

The tank's pressure will decrease becuase of the lower temprature of the water

CHARLES LAW
29. Air is comprised of 21% oxygen and 79% nitrogen. At one atmosphere of pressure what is the partial pressure of each gas. (Think dicemal point)
• Oxygen = .21 partial pressure
• Nitrogen = .79 partial pressure
30. To calculate partial pressure use the decimal percent of the gas (21% = .21), and then multiply by the the absolute pressure of where you are.
31. What is the partial pressure in atmospheres of Nitrox 32 at 106 feet in sea water?
1.34

106 feet depth / 33 feet per atmosphere = 1 atmosphere for surface pressure = 4.21 atmophseres absolute pressure

4.21 x .32 = 1.34

DALTON's LAW
32. What is the partial pressure in PSI for 21% oxygen at a depth of 78 feet in SEAWATER?
Partial pressure of oxygen is 10.37 psi absolute

78 feet depth x .445 psi per foot in sea water + 14.7 psi for surface pressure = 49.41psi absolute at depth

49.41 x .21 = 10.37

DALTON's LAW
33. What is the partial pressure in atmospheres for 21% oxygen at a depth of 78 feet in SEAWATER?
Oxygen partial pressure is .7

78 feet / 33 feet per atmosphere + 1 atmoshpere for surface pressure = 3.36 atmospheres absolute at 78 feet

3.36 x .21 = .7

DALTON'S LAW
34. What is the partial pressure in PSI of oxygen in Nitrox 32 at a depth of 106 feet in seawater?
19.79 psi absolute

106 feet x .445 psi per foot + 14.7 for surface pressure = 61.87 psi absolute pressure at depth

61.87 x .32 = 19.79 partial pressure PSI

DALTON's LAW
35. A scuba tank is accidentally filled with 1% carbon monoxide (contaminated air). If a diver breathes air from this tank at 100 feet seawater, what percentage of carbon monoxide will the diver be breathing?
1%

The percentage of carbon monoxide does not increase with depth, only the partial pressure will change with depth.
36. The density of the air you breath from a scuba cylinder at a depth of 4 atmopheres is more dense or less dense than breathing from the cylinder at the surface?
More dense...

4 times more dense since you are at 4 atmospheres
 Author: NvScubaSteve ID: 1441 Card Set: Diving Physics Updated: 2009-11-24 21:52:29 Tags: Diving Physics Folders: Description: Diving Physics Show Answers: