A police car moving at 22 m/s, chases a motorcyclist. The police man sounds his horn at 176 Hz, while both of them move towards a stationary siren of frequency 165 Hz. Calculate the speed of the motorcycle, if it is given that he does not observes any beats. [2003]

Question

Smart Achievers · Accepted Answer

(2)

$f_{1} =$ frequency of the police car heard by motorcyclist,

$f_{2} =$ frequency of the siren heard by motorcyclist.

$f_{1} = \frac{330 - v}{330 - 22} \times 176; f_{2} = \frac{330 + v}{330} \times 165;$

$∵$ $f_{1} - f_{2} = 0$ $∴$ $v = 22 m/s$

Solution

Q.
A police car moving at 22 m/s, chases a motorcyclist. The police man sounds his horn at 176 Hz, while both of them move towards a stationary siren of frequency 165 Hz. Calculate the speed of the motorcycle, if it is given that he does not observes any beats. [2003]

1 33 m/s

2 22 m/s

3 zero

4 11 m/s

Ans.
(2)

$f_{1} =$ frequency of the police car heard by motorcyclist,

$f_{2} =$ frequency of the siren heard by motorcyclist.

$f_{1} = \frac{330 - v}{330 - 22} \times 176; f_{2} = \frac{330 + v}{330} \times 165;$

$∵$ $f_{1} - f_{2} = 0$ $∴$ $v = 22 m/s$

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