- #1
GravityInTheX
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Homework Statement
As you drive at a speed of 15.0 m/s an ambulance approaches you from behind with its siren blaring at a frequency of 1022 Hz. After the ambulance has passed you the signal is now 981 Hz. If both you and the ambulance travel at a constant speed how fast was the ambulance traveling?
A. 16.0 m/s
B. 18.0 m/s
C. 20.0 m/s
D. 22.0 m/s
E. 24.0 m/s
Homework Equations
f0=fs(1/(1+vs/v))
The Attempt at a Solution
I figured I could use the ambulance's speed relative to the car, so I used the above equation for when a source is moving away from a stationary observer. I plugged in all the variables an solved for vs. I ended up getting vs being equal to 14.33. I then assumed since the speed was calculated with the car having a speed of 0 m/s, I simply added the speed of the car. That got me 29.33 m/s, which doesn't happen to be an answer choice. What am I doing wrong? Thank you so much!