posted by Armany on .
At a factory, a noon whistle is sounding with a frequency of 480 Hz. As a car traveling at 85 km/h approaches the factory, the driver hears the whistle at frequency fi. After driving past the factory, the driver hears frequency ff. What is the change in frequency ff − fi heard by the driver? (Assume a temperature of 20° C.)
I tried this , but its wrong
[2(343)(22.22) / ((343)² - (22.22)²)] (480)= 62.27 Hz
COuld someone help me out please.
The received frequency is higher (compared to the emitted frequency) during the approach, it is identical at the instant of passing by, and it is lower during the recession.
v = 85 km/h = 23.61 m/s,
V =343 m/s,
Δf =f1-f2 = f(o)•(1+v/V)-f(o)•(1-v/V)= =2•f(o)•(v/V) =
= 2•480•23.61/343 =66.08 Hz
I cant solve this can someone help me please