NAUI Diving Physics & Physiology 2

Question 1

A diver descends from the surface to 66 feet (20 m). What is the absolute pressure at that depth in ATA?

Accepted Answer

3 ATA

Answer

66 feet of seawater equals 2 atmospheres of water pressure plus 1 ATA at the surface, totaling 3 ATA.

Question 2

Which physiological condition results from breathing high partial pressures of oxygen at depth?

Accepted Answer

Oxygen toxicity

Answer

Breathing oxygen at partial pressures above 1.6 ATA can cause central nervous system (CNS) oxygen toxicity, leading to convulsions.

Question 3

What happens to the volume of a flexible air pocket in a diver's body (like a sinus) during ascent if it cannot equalize?

Accepted Answer

It expands, potentially causing barotrauma

Answer

During ascent, decreasing pressure causes trapped gas to expand according to Boyle's Law, which can rupture surrounding tissue if it cannot vent.

Question 4

A scuba tank filled to 3000 psi at 70°F is left in a hot car where temperature rises to 140°F. What happens to the tank pressure?

Accepted Answer

Pressure increases due to Gay-Lussac's Law

Answer

Gay-Lussac's Law states that at constant volume, pressure increases proportionally with absolute temperature, so the tank pressure will rise.

Question 5

What is the primary cause of nitrogen narcosis during scuba diving?

Accepted Answer

Narcotic effect of nitrogen at high partial pressures

Answer

Nitrogen at high partial pressures (typically below 100 feet) exerts an anesthetic effect on the nervous system similar to alcohol intoxication.

(NAUI) National Association of Underwater Instructors Certification Practice Test