Question

As you stand near a railroad track, a train passes by at a speed of 34.5 m/s while sounding its horn at a frequency of 215 Hz. What frequency do you hear as the train approaches you and what frequency while it recedes? Take the speed of sound in air to be 341 m/s.

Answer 1

when train is approaching then the frequency is 239.2 Hz

when train is moving away then the frequency is 195.25 Hz

Step-by-step explanation:

given,

speed of train = 34.5 m/s

Frequency of sound = 215 Hz

speed of sound = 341 m/s

a) when train is approaching

`f_1 = f((V)/(V-V_t))`

`f_1 = 215((341)/(341-34.5))`

f₁ = 239.2 Hz

when train is approaching then the frequency is 239.2 Hz

b) when the train is moving away

`f_2 = f((V)/(V+V_t))`

`f_2 = 215((341)/(341+34.5))`

f₂ = 195.25 Hz

when train is moving away then the frequency is 195.25 Hz