Two trains are traveling on the same track in the same direction. The whistles of both trains produce a 440Hz frequency sound. The lead train is traveling at 120km/hr. Both trains blow their whistles. The driver of the lead train hears that the following train has a higher frequency sound. She also notices an oscillation of 4.0 Hz.
A.) How do you explain the higher frequency sound heard by the lead train driver?
B.) How do you explain the 4.0Hz oscillation?
C.) What is the speed of the following train?
D.) The trains are 500m apart, should the lead train driver be concerned? Why or why not?
Data Given
Frequency
Speed of lead train v1 = 120 km/hr = 33.33 m/s
Let speed of the following train = v2
Part A) The higher frequency sound heard by lead train driver is due to Doppler effect and it is due to the observer and source motion.
Part B) 4 Hz oscillation must be due to because the following train is moving faster than the lead train.
Part C) Let us consider the relative speed of the trains is v
As v is the relative speed i.e.
Part D) Yes the lead train driver must accelerate to avoid the collision.
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