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JAMB Physics 1988 Question 24

Question 24

Sound

A piano wire 0.5 m long has a total mass of 0.01 kg and is stretched with a tension of 800 N. Calculate the frequency of the wire when it sounds its fundamental note.

  1. A.200 Hz
  2. B.100 Hz
  3. C.4 Hz
  4. D.2 Hz
Show the answer and explanation

Answer: A (200 Hz)

Explanation

Mass per unit length μ = 0.01/0.5 = 0.02 kg m−1. f = (1/2L)√(T/μ) = (1/1) × √(800/0.02) = 200 Hz.