The Physics of Scuba Diving By Melissa Glaser This presentation will address: Brief history of Scuba How a regulator works Air laws in effect History of Scuba 1878- Henry Fleuss invents a self contained underwater breathing unit.
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By Melissa Glaser
(This is also why you have to pop your ears as you descend.)
The part of the regulator that attaches to the tank and reduces the pressure of the air in the tank to an intermediate pressure.
First stage - diagram
The part of the regulator at the end of the hose that includes the mouthpiece. The second stage reduces the pressure in the hose to a breathable pressure.
Second stage - diagram
“For any gas at a constant temperature, the volume of the gas will vary inversely with the pressure, and the density of the gas will very directly with the pressure.”
If T= constant, then V 1/P and Density P
(Never hold your breath!)
For any gas at a constant pressure, the volume of the gas will very directly with the absolute temperature.
If P= constant, then V T
For any gas at a constant volume, the pressure of the gas will vary with the absolute temperature.
If V= constant, then P T
(keep tanks cool and don’t fill them too fast.)
The total pressure exerted by a mixture of gases is equal to the sum of the pressures of each of the gases making up the mixture, with each gas acting if it alone was present and occupied the whole volume.
(Sum of parts equals the whole!)
The amount of any given gas will dissolve in a liquid at a given temperature is proportional to the partial pressure of that gas in equilibrium with the liquid and the solubility coefficient of the gas in the particular liquid.
An increase in pressure will increase absorption
(Oxygen in your blood dissolves at a given pressure.)
Pressure can be reduced by 1/2 or less without a gas coming out of a solution.
This is like carbonation in a coke can.
Nitrogen absorbed under pressure has a narcotic effect.
(A diver can get “narked” at any depth, for no reliable reason, and it differs every dive. Past 100’ everyone is narked.)
An object is buoyed up by a force equal to the weight of the liquid it displaces