A police in a siren car moving with a velocity 20 ms^(-1) chases a thief who is moving in a car with a velocity v_(0)ms^(-1). The police car sounds at frequency 300 Hz, and both of them move towards a stationary siren of frequency 400 Hz. Calculate the speed in which thief is moving. (Assume the thief does not observe any beat).

A police in a siren car moving with a velocity 20 ms^(-1) chases a thi

1.	A police in a siren car moving with a velocity 20 ms^(-1) chases a thief who is moving in a car with a velocity v_(0)ms^(-1). The police car sounds at frequency 300 Hz, and both of them move towards a stationary siren of frequency 400 Hz. Calculate the speed in which thief is moving. (Assume the thief does not observe any beat).
Answer» Solution :The velocity of car`=20 ms^(-1)` The frequency of car = 300 Hz The frequency stationary siren = 400 Hz The speed in which thief MOVING = ? `V_(1) = 300((330-V_(0))/(330-20))` `V_(2) = 400((330 + V_(0))/330)` Both are moving towards stationary siren `THEREFORE V_(1) =V_(2)` `300((330-V_(0))/(310)) = 400 (((330 + V_(0)))/(330))` Simpliying, we GET `V_(0) = 36.99 ms^(-1)`.