Speed in same direction?

Question

when you blow your horn while driving toward a stationary listener, an increase in frequency of the horn is heard by the listener. would the listener hear an increase in the frequency of the horn is he were also in a car traveling at the same speed in the same direction as you are? explain

Answer 1

The question is asking for your understanding of the Doppler effect. The effect is as follows. A source of waves (e.g. light or sound) will appear to have a higher frequency to an observer when the source and observer are moving toward one another, and it will appear to have a lower frequency when they are moving away from one another.

Visualize the effect as follows. Think about a wave being emitted from a car toward an person far in front of the car. Let's say that the wave travels forward at the rate of 10 meters every second (imagine the crest of the wave moving forward at 10 m/s). Let's also say that wave crests are emitted every 5 seconds (1/5 Hertz is the wave's frequency). That means one crest is emitted, it moves forward 50 meters, and the next crest is then emitted. The observed receives a wave whose crests are 50 meters apart, and which arrive every 5 seconds (1/5 Hz frequency).

Now, start the car moving forward at the speed of 9 meters per second. The car is moving almost as quickly as the 10 m/s wave! Visualize what happens. The car emits a wave crest. In the next second, the crest travels forward 10 meters, but the car also travels forward 9 meters. It then emits a second wave crest, with the first crest only 1 meter in front of it. The remote observer (with the car approaching him) receives a wave whose crests are now spaced only 1 meter apart. Remember that the wave is traveling forward at 10 m/s. So the observer sees 10 wave crests striking him every second (a wave with a frequency of 10 Hz; much higher than before).

The effect can be thought of crudely as firing a machine gun at a wall. When you are stationary, the bullets make sound at certain intervals (rat..tat...tat...tat...tat...tat). When you run toward the wall and fire the bullets hit much more frequently because you are firing a bullet and then closing the distance between it and the next one fired (rat.tat.tat.tat.tat.tat).

If you were riding next to the car emitting waves, this "closing the gap" effect would not be apparent at all, since there is no relative movement between you and the source. You should hear the same frequency as if the both of you were stationary.

Answer 2

No, the listener would not hear an increase in frequency. The increase is due to the car moving in the direction of the listener. This effect also happens with light and is how we can tell if stars are moving towards us or away from us. The light is either redshifted or blueshifted.

Answer 3

What you are describing is the Doppler shift which occurs between two objects traveling at different relative velocities. If the relative velocity is 0, there is no frequency change in the sound.

Answer 4

No, because his ears would be moving along at the same speed as the sound of the horn and the sound waves would therefore not be compressed.

Answer 5

see you later because the vehicle is transferring at a consistent %, the computer virus will boost up to that % by being pushed by the air OR by landing on some thing interior the bus. notwithstanding, if the bus speeds up or brakes by surprise, the computer virus will look pushed interior an similar route because the individuals of their seats. the nice and cozy button is consistent speed vs. acceleration. once some thing reaches a consistent speed, it keeps transferring at that speed until eventually a rigidity acts on it. subsequently, once the computer virus speeds up to the consistent % of the vehicle, it is going to proceed to pass alongside with the bus until eventually it acclerates or brakes (the rigidity that transformations the speed). huge Al Mintaka