Answer:
77.6 Hz
Step-by-step explanation:
What frequency is received by a person watching an oncoming ambulance moving at 115 km/h and emitting a steady 753 Hz sound from its siren.
The given parameters are:
Observer speed = 115 km/h
Source frequency = 753 Hz
Speed of sound = 342 m/s
First convert km/h to m/s
Observer speed = (115 × 1000) / 3600
Observer speed = 31.94 m/s
The frequency received by the person will be:
F = fv / ( V - v )
Where
F = frequency received by the person
f = siren frequency
V = speed of sound
v = speed of the ambulance
Substitute all the parameters into the formula
F = (753 × 31.94) / ( 342 - 31.94 )
F = 24050.82 / 310.06
F = 77.568 Hz
Therefore, the frequency received by a person is approximately 77.6Hz