Why does sound travel faster in water than in air?
Show answer & explanation
Answer: Water resists compression much more strongly relative to its density
Water resists compression much more strongly relative to its density ✓ — Water's strong resistance to compression, relative to its density, makes pressure disturbances travel faster. Sound speed depends on both this restoring stiffness and the mass that must move; closer molecular spacing alone is not the explanation.
Water is denser, and higher density alone makes sound faster — Higher density alone would slow sound if resistance to compression stayed the same. Water is denser than air, but its much greater resistance to compression more than offsets that extra inertia.
Water makes sound waves larger, which increases their speed — Making a sound wave larger does not ordinarily make it travel faster. Loudness concerns the size of the pressure variation, whereas the medium's stiffness and density set its speed for small disturbances.
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