Question

A man standing in front of a wall fires a gun and hears an echo after 2.5s.If speed of sound is 340m/s, the distance of the man from the wall is

Answer 1

Answer:

V= 310 m/s

Explanation:

The speed of the sound is calculated as follows.

Let d be the distance between the man and the hill in the beginning.

v=

t

2×d

=

5

2×d

→eqn1

He moves 310 m towards the hill. Therefore the distance will be (d - 310) m. Therefore,

v=

3

2(d−310)

→eqn2

Since velocity of sound is same, equating (1) and (2), we get

5

2d

=

3

2(d−310)

3d = 5d - 1550

2d = 1550

d = 775 m

Hence, the velocity of sound v=

5

2×775

(substituting in equation 1)

v=310m/s

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