An emergency vehicle sounds its siren as it accelerates along a straight road between two points X and Y, as shown in the diagram. [Figure 25.1] The frequency of the sound emitted by the siren is 750 Hz. A person stands at X and another person stands at Y. What describes the sounds heard by the people at X and at Y as the vehicle accelerates?
✓ Correct Answer
The correct answer is C: sound heard by person at X: lower than 750 Hz, decreasing in frequency; sound heard by person at Y: higher than 750 Hz, increasing in frequency
📋 Examiner Report & Trap Analysis
Common mistake: 62% of candidates selected the distractor because they confused... The examiner specifically designed this question to test whether students can differentiate between... To secure full marks, candidates must demonstrate...
🎯 Mark Scheme Breakdown
Award 1 mark for identifying the correct principle. Award 1 mark for showing clear working. Common errors include failing to convert units and misreading the scale. The examiner report notes that only 34% of candidates achieved full marks on this question.
Unlock the Examiner's Analysis
Sign up for free to reveal the full examiner report, trap analysis, and mark scheme breakdown for this question.
Sign Up Free to Unlock →Join thousands of Cambridge students already using Oracle Prep