A stationary source produces a sound wave at a frequency of 100 Hz. The wave travels at 1125 feet per second. A car is moving toward the sound source at a speed of 200 feet per second.
What is the wavelength of the stationary sound source and the wavelength that a person in the car perceives?
(1 point)
Responses
wavelength of the stationary source: 13.25 ft; perceived wavelength: 11.25 ft
wavelength of the stationary source: 13.25 ft; perceived wavelength: 11.25 ft
wavelength of the stationary source: 11.25 ft; perceived wavelength: 13.25 ft
wavelength of the stationary source: 11.25 ft; perceived wavelength: 13.25 ft
wavelength of the stationary source: 11.25 ft; perceived wavelength: 9.25 ft
wavelength of the stationary source: 11.25 ft; perceived wavelength: 9.25 ft
wavelength of the stationary source: 9.25 ft; perceived wavelength: 11.25 ft
Correct response:
wavelength of the stationary source: 11.25 ft; perceived wavelength: 9.25 ft
The wavelength of the stationary sound source can be calculated using the formula: wavelength = speed of sound / frequency = 1125 ft/s / 100 Hz = 11.25 ft.
The perceived wavelength by a person in the car can be calculated using the formula for the Doppler effect: perceived wavelength = (speed of sound + speed of observer) / (speed of sound) * actual wavelength = (1125 ft/s + 200 ft/s) / 1125 ft/s * 11.25 ft = 9.25 ft.