1. The Dropper Effect
Tiffany Yang
18422148

2. Question 1:
• A police siren emits a frequency of 600.0 Hz. When
the police car approaches you at a speed of 80.0km/h,
what frequency do you perceive?

3. Solution
• The speed of the source, the policy car, is 80.0km/h=22.2m/s
• The speed of the receiver, you, is 0m/s
• The speed of the sound in air is 343m/s
• Emits frequency is 600.0Hz
• We can substitute all the information into the equation:

4. Calculation:
f=(343+0)/(343-22.2)*(600.0Hz)=641.52Hz
Does the solution
makes sense?
The solution is reasonable because as the car
approaches we hear a higher pitch.

5. Question 2:
• A police siren emits a frequency of 600.0 Hz. When the
police car moves away from you at a speed of 80.0km/h,
what frequency do you perceive?

6. Solution
We have the exactly same information as the first question:
• The speed of the source, the policy car, is 80.0km/h=22.2m/s
• The speed of the receiver, you, is 0m/s
• The speed of the sound in air is 343m/s
• Emits frequency is 600.0Hz

7. Solution
• Therefore, we can use the same equation:
• However, we need to chose the bottom sign since the car is moving
away from us.

8. Calculation:
f=(343-0)/(343+22.2)*(600.0Hz)=563.53Hz
Does the solution
makes sense?
The solution is reasonable because as the car
moves away we hear a lower pitch.