A herdsman yelling out to fellow herdsman heard his voice reflected by cliff 4s later. What is the velocity of sound in air if the cliff is 680m away?

  • A 170ms-1
  • B 136ms-1
  • C 340ms-1
  • D 680ms-1
  • E 510ms-1
jamb 1978physics

The correct answer is C. 340ms-1

Velocity = \(\frac{\text{distance}}{\text{time}}\)

echo time = halt total time

= \(\frac{1}{2}\) x 4 = 25

velocity = \(\frac{680}{2}\)= 340ms-1

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