COMEDK · Physics · 16. Waves and Sound
A car is moving towards a high cliff. The car driver sounds a horn of frequency \(f\). The reflected sound heard by the driver has a frequency \(2 f\). If \(v\) be the velocity of sound, then the velocity of the car in the same velocity units, will be
- A \(\dfrac{v}{3}\)
- B \(\dfrac{v}{2}\)
- C \(\dfrac{v}{4}\)
- D \(\dfrac{v}{\sqrt{2}}\)
Answer & Solution
Correct Answer
(A) \(\dfrac{v}{3}\)
Step-by-step Solution
Detailed explanation
Let \(v_c\) be the velocity of the car and \(v\) be the velocity of sound. The frequency of sound heard by the cliff (stationary observer) is \(f' = f \left( \dfrac{v}{v - v_c} \right)\). The cliff acts as a source reflecting this frequency \(f'\) back to the moving car (moving…
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