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JAMB Physics 1991 Question 31

Question 31

Sound

A man hears his echo from a nearby hill 2 s after he shouted. If the frequency of his voice is 260 Hz and the wavelength is 1.29 m, how far away is the hill?

  1. A.330.0 m
  2. B.335.4 m
  3. C.660.0 m
  4. D.670.8 m
Show the answer and explanation

Answer: B (335.4 m)

Explanation

v = fλ = 260 × 1.29 = 335.4 m s−1. The sound takes 1 s each way, so the hill is 335.4 m away.