A sound source is moving at 85 m/s toward a stationary listener that is standing

Question

A sound source is moving at 85 m/s toward a stationary listener that is standing in still air. In the reference frame of the source, the listener and the air are moving toward the source at 85 m/s and the source is at rest. Assume that the source emits sound at a frequency of 210 Hz. Assume also that the sound travels through still air at 344 m/s. (a) At what speed, relative to the source, is the sound traveling in the region between the source and the listener? (b) Find the wavelength of the sound in the region between the source and the listener. (c) Find the frequency heard by the listener.

Explanation / Answer

a) With respect to the source, velocity of sound is towards the listener. THen, Vs = 344 m/sec. Velocity of listener is towards the source. Then, Vl = - 85m/sec. Relative velocity of sund w.r.t to sourse = 344 + 85 = 429 m/sec.

b) Wavelength lambda = (Velocity of sound - velocity of source)/original frequency = (344 - 85)/210 = 1.233 m

c) Frequency heard by the listener is f ' = vf/(v - vs) = 344 x 210/(344 - 85) 344 x 210/259 = 278.92 Hz.

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.