Scuba Diving Physics and Physiology, Exams of Physics

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SDI Chapter 2: Physics and Physiology

What is the absolute pressure (in atmospheres/bars) at 20 meters (66 feet)?correct answer20 meters ( feet) equals 3 atm/bars What will be the volume in a ball that is filled with two-cubic-feet/liters of air at 30 meters (99 feet) when it is taken to the surface?correct answerThe ball's size will decrease by 1/2. How many more times dense is the air in a balloon at 4 atm/bar compared to the air density at the surface?correct answerThe air in the balloon will be 4x denser. If a scuba cylinder lasts two hours at sea level, how long will it last at 20 meters (66 feet)?correct answerThe cylinder will last 20 minutes. How often should a scuba diver equalize during a descent?correct answerDivers need to equalize at the surface before beginning the descent, and every couple of feet during the descent. What should you do if you experience discomfort in your ears upon descending?correct answerThe first thing you need to do is try and equalize and see if you are having a problem. If you are in fact having a problem, the next step is to stop your descent and go up a couple of feet and then try to equalize. What is a reverse block?correct answerA reverse block is when air cannot escape freely from the air space. It can cause pain or discomfort in the ears or sinuses. What should you do if you experience a reverse block upon ascending?correct answerTo fix a reverse block you need to stop your ascent and descend a couple of feet and then try to equalize. What is the most important rule in scuba diving?correct answerThe most important rule in scuba diving is to breath continuously and to avoid holding your breath.

What is the most serious injury that a diver could suffer from if they hold their breath upon ascending? correct answerRuptured lungs Which gas component in the air causes decompression sickness and narcosis?correct answerNitrogen What medical problem can occur if a diver ascends much too rapidly for nitrogen to be slowly released? correct answerThe bends or decompression sickness List at least five factors that can predispose a diver to decompression sickness.correct answerRepetitive dives, obesity, age, prior illness, and injuries (past or present) Describe the symptoms of DCS, including mild to severe signs and symptoms.correct answerMinor Signs: A rash/ crackling skin and joint pain are the most common signs. Major Signs: Difficulty breathing, dry cough, dizziness, numbness, tingling, paralysis, temporary blindness, unconsciousness, permanent disability, or death. What is the depth threshold where most scuba divers generally begin to be affected by nitrogen narcosis?correct answerThe threshold is 30 meters (100 feet). List two possible ways a diver may feel if they become "narked" at depth.correct answerThe two symptoms are extreme euphoria and extreme anxiety. What should a diver do to alleviate the symptoms of nitrogen narcosis?correct answerAscend normally until you no longer feel the effects of being "narked". Which gas causes extreme headaches and nausea, and in high enough concentrations causes unconsciousness and the lips and fingernail beds to turn bright red?correct answerCarbon monoxide What may indicate that the air in a scuba cylinder is harmful to consume?correct answerIf the smell or taste of the air if off.

What should you do if you suddenly feel sick and develop a headache during a scuba dive?correct answerIf you feel sick before the dive, then don't make the dive, if you feel sick while you are diving then abort the dive safely.