Physics - Sound Wave Question with Solution | TestHub

PhysicsSound WaveDopler's effectHard2 minPYQ_2020
PhysicsHardnumerical

A police car moving at30 m s-1, chases a motorcyclist. The policeman sounds his horn at180 Hz, while both of them move towards a stationary siren of frequency160 Hz. If it is given that the motorcyclist does not observe any beats then, calculate the speed (inm s-1) of the motorcyclist round off to two decimal places? [speed of sound=330 m s-1]

Answer:
35.02
Solution:

Speed of soundvS=330 m s-1



Case (i),

f1=f0Vs-u0Vs-us

=f0330-u330-30=180 (330-u)300

f1=180 330-u300... (i)

Case (ii),f2=160 330+u330... (ii)

There are no beats

f1=f2

180=330-u300=160330+u330

   9330-u30=8330-u33

 910330-u=811330+u

32670-99u=26400+80u

u=6270179=35.02 m s-1

Stream:JEESubject:PhysicsTopic:Sound WaveSubtopic:Dopler's effect
2mℹ️ Source: PYQ_2020

Doubts & Discussion

Loading discussions...