What are two basic physical properties that govern the velocity of sound through the medium?

What are two basic physical properties that govern the velocity of sound through the medium?

• A. Elasticity and Density
• B. Mass and Density
• C. Temperature and Pressure
• D. Mass and Elasticity

Answer: (A)

Sound travels by squeezing and stretching the medium, so how fast it goes depends on two intrinsic properties: how easily the material can be compressed (its elasticity or stiffness) and how much inertia the material has (its density). A stiffer (more elastic) medium resists deformation more and can push the disturbance along quickly, while a higher density means more mass that has to be moved, which slows the wave down. In many media, the speed is roughly proportional to the square root of the elastic modulus divided by the density, capturing the balance between stiffness and inertia. That’s why elasticity and density are the fundamental factors governing the velocity of sound. Other options mix in temperature or pressure—which affect the state of the material and thus the speed indirectly—or pair mass with density, which isn’t the primary decider of wave speed.

Sound travels by squeezing and stretching the medium, so how fast it goes depends on two intrinsic properties: how easily the material can be compressed (its elasticity or stiffness) and how much inertia the material has (its density). A stiffer (more elastic) medium resists deformation more and can push the disturbance along quickly, while a higher density means more mass that has to be moved, which slows the wave down. In many media, the speed is roughly proportional to the square root of the elastic modulus divided by the density, capturing the balance between stiffness and inertia. That’s why elasticity and density are the fundamental factors governing the velocity of sound.

Other options mix in temperature or pressure—which affect the state of the material and thus the speed indirectly—or pair mass with density, which isn’t the primary decider of wave speed.