Doppler Effect – Practice


1) The frequency of a police siren when the vehicle is stationary is 2100 Hz. What frequency will you detect if the police car is approaching you at 25 m/s and you are stationary?

2) An aircraft is flying over an airfield at 180 m/s and emitting a sound of 1500 Hz. What frequency of sound would an observer on the ground detect after the aircraft has passed the observer?

3) A vehicle is approaching a police car at 135 km/hr. A policeman directs his radar speed gun at the vehicle. If the radar gun emits a beam of frequency 25,000 Hz, calculate the frequency of the beam the radar gun would detect after striking the car:

Quick Answers:

1) 2266.7 Hz

2) 980.8 Hz

3) 25000.00313 Hz

Worked Answers: