AP Physics Multiple Choice Questions on Speed of Sound

📚 Quick Study Guide

• 💨 Speed of Sound Basics: The speed of sound depends on the medium's properties, primarily its elasticity and density.
• 🌡️ Temperature Dependence: In gases, the speed of sound increases with temperature. For air, a common approximation is $v = 331.5 + 0.6T$, where $v$ is the speed in m/s and $T$ is the temperature in Celsius.
• 🌊 Formula: The general formula for the speed of sound in a medium is $v = \sqrt{\frac{B}{\rho}}$, where $B$ is the bulk modulus (elasticity) and $\rho$ is the density.
• 📏 Solids vs. Liquids vs. Gases: Sound travels fastest in solids, slower in liquids, and slowest in gases due to differences in molecular spacing and interactions.
• 📢 Frequency and Wavelength: The speed of sound ($v$), frequency ($f$), and wavelength ($\lambda$) are related by the equation $v = f\lambda$.
• 🔊 Doppler Effect: The Doppler effect describes the change in frequency of a sound wave due to the motion of the source or the observer.

🧪 Practice Quiz

1. Which of the following factors has the greatest effect on the speed of sound in air?
   1. Pressure
   2. Humidity
   3. Temperature
   4. Frequency
2. The speed of sound in steel is greater than in air because steel has a higher:
   1. Density
   2. Temperature
   3. Elasticity
   4. Pressure
3. If the temperature of air increases, what happens to the wavelength of a sound wave produced at a constant frequency?
   1. Decreases
   2. Increases
   3. Remains the same
   4. Becomes zero
4. A sound wave travels from air into water. What happens to its speed?
   1. Decreases
   2. Increases
   3. Remains the same
   4. Becomes zero
5. What is the approximate speed of sound in air at 25°C?
   1. 331 m/s
   2. 343 m/s
   3. 350 m/s
   4. 360 m/s
6. If the frequency of a sound wave is doubled, what happens to its wavelength, assuming the speed of sound remains constant?
   1. Doubles
   2. Halves
   3. Quadruples
   4. Remains the same
7. Which of the following materials generally has the highest speed of sound?
   1. Air
   2. Water
   3. Steel
   4. Wood