Questions and Answers from SDI Quizzes

Objects under water appear: both closer and larger than they do on land What happens to colors as you descend? they appear to fade How much faster does sound travel in water, compared to air? four times as fast Water conducts heat away from your body... 25 times faster than air does T/F: A thermocline is the boundary between layers of fresh and salt water. False - it is a rapid change in temperature down a vertical column T/F: Entering shallow water causes the base of a wave to slow. true T/F: Entering shallow water forces wave energy upward, making the wave crest unstable and causing it to break. true T/F: If the bottom of a wave moves faster than the top, the wave will break. False - A 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 a surge? the back-and-forth movement of water caused by waves passing over head. T/F: In general, the best time to dive is during slack tide, the period between high and low tides. true T/F: The sun warming water near the equator, coupled with the earth's rotation, is the primary cause of permanent ocean currents. true What do you do if caught in a rip current? swim parallel to shore, until you are completely out of the rip current, then swim in towards shore T/F: Waves are measured by their height and weight. false - height and length T/F: Most aquatic animal bites result from an animal's defensive response to a perceived threat or, on rare occasions, from a case of mistaken identify. true