Scuba Diving Fundamentals: Mastering the Underwater World, Exams of Physics

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SDI Exam

Objects under water appear:correct answerCloser and larger than they do on land What happens to colors under watercorrect answerAs you descend, colors appear to fade, not intensify. Blues and grays are the last remaining colors at depth. Because sound travels faster under water:correct answerSound's increases speed under water makes it harder to determine the direction from which it is coming. Water conducts heat away from your body ___ times faster than air doescorrect answer The presence of thermoclines means thatcorrect answerdivers may require more in the way of exposure protection at depth than they will at the surface. Tides can:correct answer- make water seem deeper or shallower, stronger and difficult, adverse effect on visibility Cause of permanent ocean currentscorrect answerThe sun warming water near the equator, coupled with the earth's rotation, is the primary cause of permanent ocean currents. Wave height and lengthcorrect answerWave height is the distance from its highest point (crest) to its lowest point (trough). Wave length is the distance from crest to crest. formation of surfcorrect answerA wave encountering shallow water begins to slow at its bottom, while the top of the wave continues at its previous speed. This causes the wave to break. what is surgecorrect answerSurge is the back-and-forth movement of water caused by waves passing over head.

What causes most aquatic animal bites?correct answerAn animal's defensive response to a perceived threat & mistaken identity To be injured by an animal with poisonous spines, you must:correct answerBe the aggressor and touch the animal first. The states of buoyancy include all of the following except:correct answerPassive If you feel pain or discomfort during descent:correct answerAscend to the point where you can comfortably equalize, and only then continue your descent. Which of the following is the best way to prevent or reduce nitrogen narcosis?correct answer Any time you cannot inhale while scuba diving (such as when a regulator is out of your mouth), you must becorrect answerExhaling. What can help prevent decompression sickness (DCS)correct answersafety stops, Remain well within your dive computer's no-decompression limit, Ascend no faster than the rate allowed by the dive computer Contributing factors to decompression sickness can include:correct answerRapid ascents, 'Pushing" or exceeding your computer's no-decompression limits, Heavy exertion and/or dehydration. best way to prevent or reduce nitrogen narcosis?correct answerAvoid dives below 20 meters/66 feet. Which of the following may indicate that air in a scuba cylinder is contaminated and potentially toxic? correct answercolor, odor, taste Desirable mask features includecorrect answer1: Soft, silicone skirt. 2: Low internal volume. 3: Snug, comfortable fit.

The types of fins commonly used by recreational scuba divers includecorrect answerfull foot and open heel Basic post-dive equipment maintenance and care includescorrect answer1: Rinsing thoroughly with fresh water. 2: Allowing to dry completely. 3: Storing in a cool, dry place, away from direct sunlight. Common exposure suit types includecorrect answer1: Dive skins. 2: Wet suits. 3: Dry suits. Your body loses the greatest amount of heat through thecorrect answerHead. Which of the following is/are important features of a weight system?correct answerThere is no established minimum capacity for a weight system. So long as it has a quick-release mechanism and is easy to adjust the amount of weight used, any system that enables you to carry enough ballast to be properly weighted is fine. Popular BC styles includecorrect answerJacket-style (wraparound), Back-inflation style A regulator system may includecorrect answer1: A first stage and primary second stage. 2: An alternate air source second stage (or a connection to an alternate-air-source inflator on the BC). 3: A submersible pressure gauge (SPG), which is usually part of an instrument console. A regulator equipped with a conventional alternate-air-source second stage:correct answerConventional alternate-air-source second stages offer the benefit of being widely understood and used, and enable either diver to use either second stage. Scuba cylinders must periodically undergo:correct answervisual inspections and hydrostatic tests, at intervals determined by local laws and regulations, or prevailing standards of practice.

The minimum information most dive computers provide you with while in Dive mode include:correct answer1: Current and maximum dive depth. 2: Actual bottom time. 3: Decompression status (no-deco limit or required deco). A dive knife or cutting tool can be used tocorrect answerhelp free entangled divers or signal others under water. Steps in equipment assembly include all of the following exceptcorrect answerYou want to pressurize (not depressurize) your regulator and then test each second stage. What piece of equipment should never be allowed to dangle freely?correct answerYour alternate-air- source second stage and submersible pressure gauge or instrument console should never be allowed to dangle freely. (It would be nice to clip off the BC power inflator as well, but that is not possible.) After your buddy checks to see that your air is turned all the way on:correct answertake several deep breaths from your regulator while watching your SPG for changes in pressure. Which is the most common boat entry technique for deep water entry on large dive boats?correct answerA giant stride is the most common boat entry technique. The preferred way to remove moisture from a dust cap prior to putting it back in place is to:correct answerThe preferred way to remove moisture from a dust cap prior to putting it back in place is to wipe it with a clean, dry towel or cloth. Air passages such as your trachea (windpipe), which may contain air your body can't use, are known as:correct answerDead air spaces. Common methods for clearing water from a regulator second stage include:correct answerexhaling into the second stage and depressing the purge button. The two most common methods for recovering a regulator that has fallen behind your shoulder are:correct answerReach, Sweep

Contact lens wearers should not close their eyes when clearing a mask.correct answerIt is important that contact lens wearers close their eyes when performing this skill, to help prevent accidental lens loss. The key to venting a BC, at the surface or under water, is to:correct answerturn your body so the the exhaust valve is the highest point on the BC air cell. Before adding air to your BC under water, you must:correct answerYou need to continue to breathe normally while adding air to your BC. The three As of buoyancy control includecorrect answer1: Awareness. 2: Anticipation.

3. Action. Using your arms to swim under water:correct answerCauses you to expend energy needlessly. Among the easiest ways to don a heavy weight belt, at the surface or under water, is to:correct answerRoll into it. You can best don your scuba unit at the surface by:correct answerputting it on like a jacket or sitting on it. Which type of alternate air source does not necessarily require the donor to give up his primary second stage?correct answerConventional alternate-air-source second stage. During an independent emergency ascent, you should stop periodically and attempt to inhale through your regulator because:correct answerThe decreasing pressure may allow your regulator to function, even if it could not do so at depth. Which of the following is among the most effective means of relieving a leg cramp once it has occurred? correct answerGrasp the fin tip of the affected leg and pull towards you while straightening the leg. This stretches the calf muscle.

Techniques commonly used to navigate under water include:correct answernatural and compass navigation. Risk management is defined as:correct answerpreventing problems while at the same time having a planned response for any emergency. Activities that may increase the risk of decompression sickness include:correct answeralcohol and drug use. Any diver can signal to ______ the dive for any ________correct answerabort, reason If you and your buddy follow the same plan for dealing with buddy separation, you will end up meeting either on the _________ or ________ ___________.correct answerSurface, under water Divers should plan to ascend as soon as the first diver:correct answerreaching your maximum agreed- upon depth, so long as you do not exceed it. Should you accidentally exceed your dive computer's no-decompression limit.correct answerAir permitting, make the decompression stop indicated by your dive computer. Afterward, monitor for signs and symptoms of decompression sickness. If your buddy is unable to swim on his own, you can:correct answeryou can tow him on the surface. First aid for suspected decompression sickness may include:correct answer1: Activate the Emergency Medical Service (EMS) system and contact the Divers Alert Network (DAN). 2: Monitor the patient's vital signs.

3. Administer pure oxygen. A rip current is a narrow flow of swiftly moving water that runs ____ to shore.correct answerperpendicular

Rip currents form whencorrect answerwater flowing out to sea is funneled through a narrow restriction, such as two sandbars or a break in a coral reef. A scuba cylinder that normally lasts one hour at the surface will last _______ minutes at 20 meters/ feet.correct answer A repetitive dive is any dive:correct answerany dive made within 24 hours of a previous dive, or in which your computer indicates there is residual nitrogen left in your system from a prior dive. Should you become entangled under water:correct answerdo not struggle in an effort to free yourself. If you cannot easily untangle yourself, have your buddy do it for you. Seasickness medications are only effective if taken well in ____ of the onset of symptoms.correct answeradvance