As materials become more dense the speed of sound in the material ______.

As materials become more dense the speed of sound in the material ______.

• A. Increases
• B. Decreases
• C. Stays the same
• D. Changes

Answer: (B)

The main idea is that how fast sound travels in a material depends on how stiff the material is compared to how much mass it has. Sound moves by particles pulling on their neighbors, so heavier particles (higher density) require more effort to accelerate, which slows the propagation of the wave. In many simple descriptions, the speed is proportional to the square root of stiffness divided by density. If you raise density while stiffness stays about the same, the speed drops. So, as materials become more dense (without a proportional increase in stiffness), the speed of sound tends to decrease.

The main idea is that how fast sound travels in a material depends on how stiff the material is compared to how much mass it has. Sound moves by particles pulling on their neighbors, so heavier particles (higher density) require more effort to accelerate, which slows the propagation of the wave. In many simple descriptions, the speed is proportional to the square root of stiffness divided by density. If you raise density while stiffness stays about the same, the speed drops. So, as materials become more dense (without a proportional increase in stiffness), the speed of sound tends to decrease.