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# Science Of Diving

### SSI course The Science of Diving

TermDefinition
Pressure Pressure=Force/Area or P=F/A
Atmospheric Pressure Air pressure at sea level. expressed as 1 ATA
Hydrostatic Pressure The weight exerted by a fluid due to the force of gravity 1 ata=34 feet of fresh water (ffw) 1 ata=33 feet of salt water (fsw)
Fresh water exerts 14.7 psi/34 ffw = .432psi/ft
Salt Water exerts 14.7 psi/33 fsw = .445psi/ft
Gauge pressure pressure does not take in to account atmospheric pressure (mostly for divers information)
Absolute Pressure The total pressure exerted on an object Absolute pressure (ata)=Depth (fsw)/(33fsw/ata)+1
Formulas for Converting Pressure Pressure(ata)=(D/33ft) + 1 D=(ata)-1) x 33 ft
Convert from Celsius to Fahrenheit F=(C x 1.8) + 32
Convert from Fahrenheit to Celsius C=(F - 32) / 1.8
Degrees Kelvin Degrees Kelvin=C + 273
Degrees Rankine Degrees Rankine = F + 460
1 liter 1000 Cubic centemeters
1 cubic foot 1728 cubic inches
1 cubic yard 27 cubic feet
1 statute mile (land) 5280 feet
1 nautical mile 1.151 Statute Miles
Density Mass/Volume
Components of Air Nitrogen = 78.08% Oxygen = 20.94% Argon = 0.93% Carbon Dioxide = 0.03% Other Gases = 0.02%
Hypoxia Not enough O2 to support life at low partial pressures= unconsciousness and death
Hyperocia Too much O2 at high partial pressure. = pulmonary ore central nervous system toxicity.
Pressure Always referred to as (P) P= (Depth/33) + 1 Depth =(P-1) x 33
Boyle's Law If the temperature remains constant the pressure and volume of any gas are inversely related, ie.. as the pressure increases, the volume decreases and if the volume increases the pressure decreases.
Boyle's Law formula P1 x V1 = P2 x V2
Charles' Law If the pressure of a gas is constant, then the volume of the gas varies directly with temperature.
Charles' Law formula - Constant volume P1 / T1 = P2 / T2
Charles' Law formula - Constant pressure V1 / T1 = V2 /T2
General Gas Law formula (P1 x V1) / T1 = (P2 x V2) / T2
Henry's Law The amount of gas that will dissolve in a liquid is directly proportional to the partial pressure of that gas, given that the temperature and the molecular movement (agitation) of the liquid are constant
Dalton's Law In a mixture of gases, the total pressure (P) of the mixture equals the sum of the partial pressures (pp) of the individual gases. ppgas 1 + ppgas 2 = P
Dalton's Law formula ppgas = P x fgas fgas = the fraction of gas in the mixture expressed as a decimal also P = ppgas / fgas
Buoyancy is the force by which an object floats or sinks, there are three kinds of buoyancy:
Neutral Buoyancy Will remain suspended at the same depth it was placed.
Negative Buoyancy Will sink when placed in fluid.
Positive Buoyancy Will rise toward the surface, at the surface will remain floating.
Archimedes' Principle An object placed in liquid will be buoyed up by a force equal to the weight of the liquid it displaces.
Archimedes' formula B = (VO x DL) - WO B = Bouyant force VO = Volume of the object DL = Density of the liquid WO = Weight of the object
Density of salt water 64 lbs /cu ft
Density of fresh water 62.4 lbs / cu ft
Surface air Consumption Rate SAC = (AC / T) / D SAC = Surface air consumption rate AC = Air consumed in psi D = Depth expressed in bar or (fsw /33) =1 T = time
Formula to find time T = AC /(SAC x D)
Formula to find the air Consumed AC = SAC x D x T
What changes the appearance of the environment under water Refraction Diffusion Turbidity Absorption
Sound Travels 4x faster in water than it does in air and sound delay is 1/4 that of air so it is hard to determine which way the sound comes from.
Created by: nemery12