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JAMB Physics 1992 Question 20

Question 20

Waves

The equation of a wave is y = 0.005 sin [π(0.5x − 200t)] where x and y are in metres and t is in seconds. What is the velocity of the wave?

  1. A.4000 m s−1
  2. B.400 m s−1
  3. C.250 m s−1
  4. D.40 m s−1
Show the answer and explanation

Answer: B (400 m s−1)

Explanation

For y = A sin(kx − ωt) the wave speed is v = ω/k. Here v = 200/0.5 = 400 m s−1 (a common factor π cancels).