Question

In: Physics

A person is driving his car on some road and suddenly a police car stops him...

A person is driving his car on some road and suddenly a police car stops him for speeding, the police-detected radar gun emits a wave whose frequency is 8.0 × 109 ??.

1. How do you think the mechanism by which you know how fast a moving car can go works?

2. Does it depend on the speed of the police car? Does it depend on the speed of the person's car?

3. Does it depend on the two speeds?

4. What role does frequency play?

5. What function does the wave velocity fulfill?

Solutions

Expert Solution

(a) Radar gun works on the principle of the radar gun. In a radar gun, we emit a radio frequency wave, this wave will strike the vehicle and reflected back and radar gun will recieve back the wave. Radar gun will then analyse the frequency of the wave recieved. As per Doppler effect, there will be a shift in recieved frequency when there is a relative motion between source and reflector.

(b) Speed of person car relative to police car is given as

             

Where delta f is shift in frequency, f is the frequency and c is the speed of wave.

Since vr is the relative velocity, so yes it depends on both police car speed and speed of person car.

(c) yes it depend on two speeds.

(d) Observed frequency is directly proportional to the transmission frequency

(e) As already specified in above equation, relative speed depends of the speed of wave

genius_generous answered 1 year ago
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