Homework SourseA car is traveling toward you at 40 mihr The car horn produc
A car is traveling toward you at 40 mi/hr. The car horn produces a sound at a frequency of 480 Hz. What frequency do you hear? Assume that the sound velocity in air is 1090 ft/s.
A car is traveling toward you at 40 mi/hr. The car horn produces a sound at a frequency of 480 Hz. What frequency do you hear? Assume that the sound velocity in air is 1090 ft/s.
Solution
Speed of car v = 40 mi / hr
= 40 x1609 m / 3600 s
= 17.8777 m/s
Speed of sound in air V = 1090 ft / s
= 1090 x0.3048 m / s
= 332.232 m/s
Actual frequency f = 480 Hz
Required frequency f \' = ?
From Doppler effect , f \' = [(V-0) /(V-v)] f
= [332.232 /(332.232 - 17.8777)] 480
= 507.2 Hz
