If a medium becomes stiffer while density remains the same, what happens to propagation speed?

If a medium becomes stiffer while density remains the same, what happens to propagation speed?

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

Answer: (A)

Propagation speed depends on how stiff the material is and how dense it is; with density fixed, increasing stiffness makes waves travel faster. When a medium is stiffer, it resists deformation more strongly and can restore its shape after a disturbance more quickly, so pressure changes propagate through it more rapidly. This is captured by the general relationship where speed is proportional to the square root of stiffness divided by density; keeping density constant, increasing stiffness raises the speed. In ultrasound terms, tissues with higher stiffness transmit sound more quickly than softer ones at the same density.

Propagation speed depends on how stiff the material is and how dense it is; with density fixed, increasing stiffness makes waves travel faster. When a medium is stiffer, it resists deformation more strongly and can restore its shape after a disturbance more quickly, so pressure changes propagate through it more rapidly. This is captured by the general relationship where speed is proportional to the square root of stiffness divided by density; keeping density constant, increasing stiffness raises the speed. In ultrasound terms, tissues with higher stiffness transmit sound more quickly than softer ones at the same density.