You are traveling slightly over the speed limit when you see a police car behind you in your rear view mirror.He immediately changes lanes and passes you by.You are so nervous after the police car passes you that you pull off to the side of the road and stop.Now you hear a siren,this time from an ambulance approaching from behind.The frequency you hear its siren is 1280 Hz.Once it passes,its frequency is 1080 Hz.What is the speed of the ambulance?
A)20.04 m/s
B)25.45 m/s
C)29.07 m/s
D)31.12 m/s
E)33.69 m/s

Question

Quizplus · Accepted Answer

The Doppler effect formula for sound can be used to calculate the speed of the ambulance. The observed frequency when the source is approaching is higher than when it is moving away. Using the formula for the Doppler effect and solving for the speed of the source, the speed of the ambulance is approximately 29.07 m/s.

You Are Traveling Slightly Over the Speed Limit When You