A person is standing between 2 vertical cliffs and 640 m away from the nearest cliff he shouted . he heard the first echo after 4 sec and the second echo 3 sec later. calculate

a) velocity of sound in air

b) distance between the cliffs

Solution:

According to question,x=640m

Consider that the echo of 4 sec and 3 sec are produced by are produced by cliff A and B. 

Then 2 x 640=speed of sound x 4

Speed of sound=2 x 640/4=320m/s

Again 2y=320 x 3=960

y=480m

Distance between cliffs=x+y=640+480=1120m

​Hence, distance between two cliff = 640 + 1120 = 1760m.

  • 6

speed = distance / time

a) velocity of sound in air = 640 / 2

  =  320 m/s

b) speed = s / t

  320 = s / 1.5

  s = 320 * 1.5

  s = 480 m

now total distance between two cliffs : 640 + 480

  = 1120 m

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