Question

A stone is dropped from cliff into a lake 80 m deep. Another cliff which is 200 m away from the lake
reflects the sound of splash . What is the time difference between the sounds of the first splash
and echo of splash? Take speed of sound is 340 ms1 and g = 10 ms2

Answer 1

Answer:

Option b

Explanation:

Correct option is

B

19.6 m

Time taken by the stone to reach the water surface

t

1

=

g

2h

, where h is the height of the well.

Time taken by the sound to reach the observer

t

2

=

350

h

Total time

t=t

1

+t

2

=

g

2h

+

350

h

=

4.9

h

+

350

h

=2.056

Solving the above Eqn. we get

h=19.6 m