Question

A person standing between two vertical cliffs and 680 m away from the nearest cliff,shouted. He heard the first echo after 4s and the second echo 3s later. Calculate the distance between the two cliffs

Answer 1

Answer: 1190m

Explanation:

First case,

the difference b/w the person and the cliff=680m

t1=4s

speed of sound(v) = ?

d1=vt1/2

680=4v/2

after calculating,

v=340 m/s

2nd case,

t2= 3s

speed of sound(v) = 340 m/s

d2=?

d2=vt2/2

d2=(340*3)/2

after calculating,

d2=510m

total distance = d1+d2

=680+510

=1190m

Answer 2

Answer: 1870 m

Explanation: Answer :

(a) 340 m//s

(b) 1870 m.

Solution :

Here, t1=4sandt2=3s,d1=680m

(a) As d1=vt2,v=2d1t1=2×6804=340m/s

(b) As d2=v(t1+t2)2=340(4+3)2=1190m

Distance between two cliffs, d=d1+d2=680+1190=1870m.