Doppler Effect for Approaching Source

Steps:

• Use formula: observed frequency f' = f × (v / (v - vs)), where f = 1000 Hz, f' = 1500 Hz, v = 330 m/s.
• Set up equation: 1500 = 1000 × (330 / (330 - vs)).
• Simplify: 1.5 = 330 / (330 - vs).
• Solve: 330 - vs = 330 / 1.5 = 220, so vs = 330 - 220 = 110 m/s.

Why A is correct:

• Matches Doppler formula calculation for source speed yielding exact 50% frequency increase.

Why the others are wrong:

• B: Yields f' ≈ 1875 Hz, overestimating frequency shift.
• C: Yields f' ≈ 3000 Hz, doubling frequency unrealistically.
• D: Yields infinite f', impossible as source matches sound speed.

Final answer: A