Which combination of properties would generally increase the speed of sound in a medium?

Which combination of properties would generally increase the speed of sound in a medium?

• A. High Elasticity and High Density
• B. High Elasticity and Low Density
• C. Low Elasticity and High Density
• D. Low Elasticity and Low Density

Answer: (B)

Understanding the speed of sound in a medium hinges on how easily the medium can be compressed (elasticity) and how much mass there is to move (density). A stiffer material transmits pressure changes more quickly, while a lighter material offers less inertia to resist motion. The speed of sound is proportional to the square root of stiffness divided by density, so increasing stiffness and decreasing density both push the speed higher. That’s why the combination of high elasticity with low density gives the fastest sound transmission. The other combinations either raise density or lower elasticity, which slows the wave because more inertia or less stiffness hinders rapid propagation.

Understanding the speed of sound in a medium hinges on how easily the medium can be compressed (elasticity) and how much mass there is to move (density). A stiffer material transmits pressure changes more quickly, while a lighter material offers less inertia to resist motion. The speed of sound is proportional to the square root of stiffness divided by density, so increasing stiffness and decreasing density both push the speed higher.

That’s why the combination of high elasticity with low density gives the fastest sound transmission. The other combinations either raise density or lower elasticity, which slows the wave because more inertia or less stiffness hinders rapid propagation.