Question

A train is moving at the speed of 72 km per hour towards station surrounding visitor of frequency 640 words what is the apparent frequency of the register as heard by the man and the flat pump when the train approaches and received from him speed of the sound 300 m per second

Answer 1

Solution:  

Apparent frequency= f.

v = rate of sound = 330 m/s

Frequency of the sound supply = f₀ = 600 Hz

Velocity of the supply (train) = Vs = + 72 kmph = + 20 m/s

velocity of the observer = Vo = 0

f =  $\frac{v+v_{0} }{v+v_{s} }$

(i) f = 600× 330+0 /330-20

f= 600×330/310

f= 600× 1.0645

f= 683.78 Hz  

(ii) f= 600 ×330+0 /330+20

f= 600 × 330 /350

f= 600× 0.9428

f= 571.71 Hz  

When the train approaches, the frequency are additional and it'll be less because the train goes away.

=============

@GauravSaxena01