A sound source moves with constant speed on a circle whose centre is occupied by a stationary observer. The source emits a constant frequency f. Neglect wind and relativistic effects. What frequency is heard by the observer?
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Question

A sound source moves with constant speed on a circle whose centre is occupied by a stationary observer. The source emits a constant frequency f. Neglect wind and relativistic effects. What frequency is heard by the observer?

Options

G1 Physics · Accepted Answer

The distance between source and observer is constant. The source velocity is always tangent to the circular path and therefore perpendicular to the radius joining source and observer. Hence the radial velocity component is zero at every instant. Therefore there is no classical Doppler shift and the observer hears f' = f. Correct option: D.