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:
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.