SDI Open Water Scuba Diver Practice Exam

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Prepare for the SDI Open Water Diver Exam. Dive into multiple choice questions, hints, and explanations to gear up for the certification. Start your underwater adventure today!

Each practice test/flash card set has 50 randomly selected questions from a bank of over 500. You'll get a new set of questions each time!

Practice this question and more.

How much faster does sound travel in water relative to air?

2 times
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4 times
5 times

The correct answer is: 4 times

Sound travels significantly faster in water than in air due to the differences in density and elasticity between the two mediums. In general, sound waves move more quickly in denser materials because the molecules are more closely packed, allowing them to transmit vibrations more effectively. In air, the speed of sound is approximately 343 meters per second (m/s) at 20 degrees Celsius, while in water, sound travels at about 1,480 m/s. To compare these two values, the speed of sound in water is roughly four times faster than in air. Understanding this difference is crucial for divers as it affects underwater communication and the way sound travels in the aquatic environment. This knowledge helps divers to better interpret sounds and communicate in underwater situations, as sound directionality and speed can impact safety and navigation.