Doppler shift for a moving source
A source emitting 500 Hz moves toward a stationary listener at 34 m/s. If the speed of sound is 340 m/s, what frequency does the listener hear?
Answer D: explanation for every choice
A
This uses the formula for a source moving away (340 + 34 in the denominator).
B
500 Hz ignores the Doppler shift.
C
This uses the formula for a moving listener, (v + vo)/v, which doesn't apply to a moving source.
D
Correct. f′ = f·v/(v − vs) = 500 × 340/306 ≈ 556 Hz.
TakeawayMoving source: f′ = f·v/(v ∓ vs). Use minus when approaching.
Equation usedDoppler effect
Next question →Reviewed 2026-11-05 by a medical student. Spot an error? Report it with question ID cp130.