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Q19 (CDS-II/2021) Science & Technology › Basic Science (Physics, Chemistry, Biology) › Waves and acoustics Answer Verified

A sound wave has a freency of 4 kHz and wavelength 30 cm. How long will it take to travel 2.4 km ?

Result
Your answer: —  Â·  Correct: A
Explanation

The correct answer is Option 1 (2.0 s). To determine the time taken, we first calculate the speed of the sound wave using the wave equation: Speed (v) = Frequency (f) × Wavelength (λ).

  • Frequency (f): 4 kHz = 4000 Hz
  • Wavelength (λ): 30 cm = 0.3 m
  • Speed (v): 4000 Hz × 0.3 m = 1200 m/s

Once the speed is determined, the time taken to travel a specific distance is calculated using the formula: Time = Distance / Speed.

  • Distance (d): 2.4 km = 2400 m
  • Time (t): 2400 m / 1200 m/s = 2.0 s

Option 1 is correct as it accurately follows the conversion of units to the SI system and the application of fundamental physics formulas. Other options are incorrect as they result from mathematical errors or failing to convert kHz to Hz or cm to meters.

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