It increases.
Explanation
Sound is a mechanical longitudinal wave that requires a material medium for propagation. The speed at which sound travels through a medium is governed by the medium's physical properties, specifically its elasticity (bulk modulus) and density.
Detailed Analysis
The speed of sound ($v$) in a medium is mathematically represented as:
$v = \sqrt{\frac{E}{\rho}}$
Where:
- $E$ represents the modulus of elasticity (stiffness) of the medium.
- $\rho$ represents the density of the medium.
When comparing a gaseous medium (air) to a liquid medium (water):
- Elasticity Factor: Liquids are much less compressible (more elastic) than gases. The bulk modulus of water is significantly higher than that of air. This factor tends to increase the speed of sound.
- Density Factor: Liquids are denser than gases. While higher density theoretically lowers the speed (as seen in the denominator of the formula), the increase in elasticity in liquids is far greater in magnitude than the increase in density.
Consequently, the ratio $\frac{E}{\rho}$ is much larger for liquids than for gases. Therefore, sound travels significantly faster in water (approximately 1,480 m/s) than in air (approximately 343 m/s).
Key Takeaway: The speed of sound depends on the phase of matter and generally follows the order: Solids > Liquids > Gases.