This is a Doppler Effect case. When the source moves toward a stationary observer: 𝑓′ = 𝑓/1−𝑣𝑠/𝑣 = 500/1−20/340 = 500/0.9412 ≈ 531 Hz You hear a higher frequency as the car approaches.
A car is moving at 20ms-¹ along a straight road and sounds its horn at 500 Hz. What frequency do you hear aa the car is approaching you? (Use speed of sound = 340ms-¹)
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Question context
This question is part of ⚙️ Mechanical Eng within the broader 🛠️ Engineering Essentials subject and appears in the ETEA Educational Testing and Evaluation Agency preparation collection. Reviewing the answer together with nearby questions helps reinforce the underlying concept and identify how it may appear in competitive exams.