2021 · Q19
A sound wave has a frequency of 4 kHz and wavelength 30 cm. How long will it take to travel 2·4 km?
General KnowledgePhysics
- A2·0 s
- B0·6 s
- C1·0 s
- D8·0 s
Explanation
Wave speed v = f * lambda = 4000 Hz x 0.30 m = 1200 m/s. The time to travel 2.4 km is distance divided by speed: 2400 m / 1200 m/s = 2.0 s. The other options result from misplacing the decimal in the wavelength or the distance conversion.