Traveling waves

# 16 Traveling waves (Overview)

Sources of sound vibrate. A short time later, the disturbance arrives at a detector and the detector vibrates in response to the disturbance. But what happens in between source and detector? What does sound look like as it travels?

Sound has a lot in common with ripples on a pond. Dip your finger in a pond and ripples travel outward from the the source. Dip your finger repeatedly, and a series of ripples travels outward from the source. Sound “ripples” are almost impossible to see directly, but there’s plenty of reason to believe they exist. A wave model for sound raises lots of questions about sound?

• What role does air play in sound?
• What, exactly, is moving when sound travels from place to place?
• How are the sound “ripples” made? What do they look like?
• How are loud sounds different from those quiet sounds?
• How are high pitch sounds different than low pitched ones?

### Traveling Waves: Learning Objectives

• Distinguish between the motion of a wave and motion of the material in which the wave travels
• Distinguish between pulse and wave
• Describe the motion of a sound wave
• Describe the motion of the air particles in a sound wave
• Distinguish between longitudinal and transverse waves
• Define and describe wavelength, frequency and amplitude for L-waves and T-waves
• Explain the relationship among wave speed, frequency and wavelength
• Identify things that affect the speed of a wave (and things that don’t)
• Apply the equations $d=vt$ and $\lambda = \dfrac{v }{f}$ to solve numerical and non-numerical problems
• Describe Doppler effect and apply the Doppler effect equation: