If a medium becomes denser while stiffness remains unchanged, what happens to the propagation speed?

If a medium becomes denser while stiffness remains unchanged, what happens to the propagation speed?

• A. Increases
• B. Decreases
• C. Stays the same
• D. Becomes unpredictable

Answer: (B)

The speed of a wave in a medium depends on how stiff the medium is and how dense it is. Stiffer media transmit waves faster, while denser media slow them down. If density increases but stiffness stays the same, the inertia opposing motion grows, so the propagation speed decreases. In formula terms, for many wave types the speed is proportional to the square root of stiffness divided by density, so increasing density without changing stiffness lowers the speed. Therefore, the propagation speed decreases.

The speed of a wave in a medium depends on how stiff the medium is and how dense it is. Stiffer media transmit waves faster, while denser media slow them down. If density increases but stiffness stays the same, the inertia opposing motion grows, so the propagation speed decreases. In formula terms, for many wave types the speed is proportional to the square root of stiffness divided by density, so increasing density without changing stiffness lowers the speed. Therefore, the propagation speed decreases.