# Diving Physics

 Pounds per Square Inch (PSI) per foot in SEAWATER .445 psi per foot Pounds per Square Inch (PSI) per foot in FRESH WATER .432 psi per foot Atmospheric pressure at SEA LEVEL 14.7 PSI or 1 Atmosphere absolute Specific Gravity of PURE WATER 1.0 If an object sinks in water the object's buoyancy is... NEGATIVE If an object floats in water the object's buoyancy is... POSITIVE If an object neither sinks nor floats in water the object's buoyancy is... NEUTRAL "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 How much does one cubic foot of SEAWATER weigh? 64 pounds How much does one cubic foot of FRESH WATER weigh 62.4 pounds 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) 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 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 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) 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 What is the fomula for Boyles Law? P1 x V1 = P2 x V2works as: P1 x V1 / P2 = V2orP1 x V1 / V2 = P2 What gas law uses this fomula? P1 x V1 = P2 x V2 T1 = T2 Charles Law Add what number to degrees Farenheit to determine Rankine? 460 Example 80 F + 460 = 540 degree Rankine 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) What is the GAUGE pressure in PSI for a depth of 106 feet in SEAWATER 47.17 PSI 106 feet x .445 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 What is the GAUGE pressure in ATMOSPHERES for 93 feet in FRESHWATER 2.73 93 feet / 34 feet per atmosphere How many feet of depth equals one atmosphere in SEAWATER 33 feet for each 33 feet of depth pressure increases by 1 atmosphere 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 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 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 psiV1=80 cubic foot tankT1= 540 (80+460 to equal rankine)P2= UNKNOWNV2=80 cubic foot tankT2= 500 (40+460 to equal rankine) The math is: 3000 x 500 / 540 we can delete the volume becuase it does not change 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 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 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 pressureNitrogen = .79 partial pressure 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. 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 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 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 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 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. 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 AuthorNvScubaSteve ID1441 Card SetDiving Physics DescriptionDiving Physics Updated2009-11-24T21:52:29Z Show Answers