ARDMS Ultrasound Physics & Instrumentation Practice Exam

Which of the following is true regarding sound speed in different media?

1. Sound travels faster in solids than liquids

2. Sound travels faster in gases than solids

3. Sound speed is constant regardless of the medium

4. Sound speed increases with decreasing temperature

The correct answer is: Sound travels faster in solids than liquids

The statement that sound travels faster in solids than in liquids is accurate because the speed of sound is influenced by the medium through which it travels. In solids, molecules are closely packed together, allowing sound waves to transfer vibrations more efficiently between particles. This close proximity facilitates faster propagation of sound waves as compared to liquids, where the molecules are further apart, thereby resulting in a slower transmission of sound. In terms of sound speed, this principle applies universally across different states of matter. Generally, sound travels slowest in gases due to the significant distance between molecules, and faster in liquids, with the greatest speed achieved in solids. Therefore, the correct choice highlights this fundamental property of acoustic wave propagation in various media. The other choices reflect misunderstandings about sound speed. For instance, sound does not travel faster in gases than in solids, nor is sound speed constant across different media—it varies significantly. Additionally, as temperature decreases, sound speed in a medium like air actually decreases because colder temperatures lead to lower energy levels and slower molecular motion, contrary to the option suggesting an increase in sound speed with decreasing temperature.