Is there an appreciable Dopper effect when the motion of the source is at right angles to a listener? Explain.

Answer 1

No, because the source is neither approaching or moving away from the listener at that moment

Answer 2

Of course not, because the Doppler effect only works when the source and listener are approaching or going away from each other. When the motion of the source is at right angles, the listener is in the center of a circle, and the source is going around the circle. The angle is always a right angle (tangent to the circle), and the distance is always the same. Because of this last, no Doppler effect.

Answer 3

Assuming that the source is moving in a straight line. I would say Yes. Intitially the doppler effect would be negligible but as the source goes further away from you, the angle becomes irrelevant, and you will observe a decrease in the frequency of the sound. If the source is moving in a Circle around you, I would think that there would not be any doppler effect.

Answer 4

No there is not. As the train approaches the pitch goes up and as it departs the pitch goes down. At the instant between approaching and leaving, the pitch is the same.

You can also think about it as the train going around you in the circle. The sound waves would be compressed in the front of the train and streched out behind the train, but at the sides of the train the distance between the wave peaks would be unaffected.