Apparent frequency of reflected wave

In summary, the question involves a police car P and car T moving to the right, with P's siren emitting a frequency of 1000hz. The apparent frequency of the siren heard by driver T is 967hz, and the apparent frequency of the reflected wave heard by driver P is 941hz. However, it is more logical for driver P to hear the reflected wave, not driver T.
  • #1
desmond iking
284
2

Homework Statement



A police car P with its siren on is chasing car T . The frequency of the siren is 1000hz. The speed of police car P is 30m/s . and the speed of car T is 40m/s . What's the apparent frequency of the siren heard by driver T > the ans is 967hz . I managed to get the ans for this.
But i didnt managed to get the ans for part b .
here's part b :
What's the apparent frequency of the reflected wave heard by driver T ? the ans is 941 hz. p/s : i assume both P and T are moving to the right.

Homework Equations





The Attempt at a Solution


apparent frequency of the siren heard by driver T = ((330-40)/(330-30))x 1000 = 967hz.

b ) apparent frequency of the siren emitted by P to the left = (330/(330+30)) x 1000 = 917hz.

apparent frequency of the siren reflected from the right and heard by T after reflection = ((330-40) / (330-30) ) x 917hz = 886hz . i am not sure which direction of the sound wave is reflected. can somoene explain on this?
 
Physics news on Phys.org
  • #2
Are you sure the question is asking about driver T hearing the reflected wave? It makes more sense that driver P hears the wave reflected off of T.
 
  • Like
Likes 1 person
  • #3
vela said:
Are you sure the question is asking about driver T hearing the reflected wave? It makes more sense that driver P hears the wave reflected off of T.

yes the question asking T heard the wave
 
  • #4
Driver T can't hear the reflected wave- it is moving away from him.
 
  • #5
HallsofIvy said:
Driver T can't hear the reflected wave- it is moving away from him.

so is the question wrong?
 
  • #6
Sounds like it. Try calculating the frequency P hears for the reflected wave.
 

1. What is the apparent frequency of a reflected wave?

The apparent frequency of a reflected wave refers to the perceived frequency of a wave that has been reflected off a surface. It may differ from the actual frequency of the wave due to factors such as the velocity of the reflecting surface and the relative motion between the source of the wave and the reflecting surface.

2. How is the apparent frequency of a reflected wave calculated?

The apparent frequency of a reflected wave can be calculated using the Doppler effect equation, which takes into account the velocity of the reflecting surface, the velocity of the source, and the speed of the wave. It can also be calculated using the formula for the reflected wave's frequency, which takes into account the angle of incidence and the speed of the wave.

3. What factors affect the apparent frequency of a reflected wave?

The apparent frequency of a reflected wave can be affected by a variety of factors, including the velocity of the reflecting surface, the velocity of the source, the speed of the wave, and the angle of incidence. Other factors such as the medium through which the wave is traveling and the temperature can also have an impact on the apparent frequency of a reflected wave.

4. Why does the apparent frequency of a reflected wave change?

The apparent frequency of a reflected wave changes because of the Doppler effect, which causes the perceived frequency of a wave to change when there is relative motion between the source of the wave and the observer. In the case of a reflected wave, the relative motion is between the source and the reflecting surface, resulting in a change in the apparent frequency of the wave.

5. How does the apparent frequency of a reflected wave affect sound perception?

The apparent frequency of a reflected wave can have a significant impact on sound perception, as it can alter the pitch and loudness of a sound. For example, when a sound wave reflects off a moving surface, the apparent frequency may be higher or lower than the actual frequency, resulting in a change in the perceived pitch of the sound. This phenomenon is commonly experienced in echo chambers or when standing near a moving vehicle.

Similar threads

Apparent frequncy of sound heard?
    • Introductory Physics Homework Help
Replies
1
Views
1K
Frequency of the sound heard by the passanger in the car
    • Introductory Physics Homework Help
Replies
2
Views
1K
Frequency of varaiation of sound intensity
    • Introductory Physics Homework Help
Replies
17
Views
2K
Doppler shift of an approaching source with interference problem
    • Introductory Physics Homework Help
Replies
4
Views
2K
Calculating Frequency of Siren Heard by Truck After Police Passes
    • Introductory Physics Homework Help
Replies
6
Views
6K
The observed frequency of a 1,200 Hz wave
    • Introductory Physics Homework Help
Replies
5
Views
5K
What is the frequency of the wave reflected by the fish?
    • Introductory Physics Homework Help
Replies
2
Views
981
Understanding Radio Waves & Oxygen Absorption at 60GHz
    • Introductory Physics Homework Help
Replies
1
Views
1K
Wave, finding the velocity of the incoming car.
    • Introductory Physics Homework Help
Replies
2
Views
916
Waves on a String -- Minimizing reflections from the far end (ring on a bar)
    • Introductory Physics Homework Help
Replies
1
Views
969

Hot Threads

Recent Insights

Back
Top