ASVAB (Armed Services Vocational Aptitude Battery)General Science (GS)Hard
A student is investigating the properties of sound waves. She observes that sound travels faster through water than through air. Which physical property of the medium primarily explains this difference in speed?
- AHumidity
- BElasticity (or stiffness)
- CTemperature
- DDensity
Show answer & explanationAnswer & explanation
Correct answer: B. Elasticity (or stiffness)
The speed of sound in a medium is primarily determined by its elasticity (or stiffness) and density. While water is denser than air, its significantly higher elasticity (resistance to deformation) allows sound waves to propagate much faster because the particles are more tightly coupled and transmit vibrations more efficiently.
Why the other options are wrong
- A. Humidity affects sound speed in air but is irrelevant for the air-water comparison.
- C. Temperature affects sound speed, but it's not the primary reason for the vast difference between air and water.
- D. While density plays a role, increased density alone would slow sound. It's the interplay with elasticity that's key.
Speed of Sound in Mediums
The speed at which sound waves propagate through a medium, determined primarily by the medium's elasticity and density.
- Generally fastest in solids, then liquids, then gases.
- Higher elasticity (stiffness) leads to faster sound speed.
- Higher density tends to slow sound, but elasticity is often dominant.
Memory trick: Elasticity makes it fast, Density holds it back.