Question

A boy is standing in the middle of a big square field . There is a tall building on one side of the field. He explodes a cracker and hear its echo 0.45 later . What is the size of square field

Answer 1

•A boy is standing in the middle of a

big square field . There is a tall

building on one side of the field.

He explodes a cracker and hear its

echo 0.45 later . What is the size of

square field ?

Let, the length of the side of the

square field be a, thus distance

between the boy and the field will

be a/2.

Here,

-Time of echo t 0.4 s

-Velocity of sound=330 m/s

-Distance D = a/2

Now we have,

V = 2D/t

=> 330 (2xa/2)/0.4

=> a = 132 m

Thus the length of the side of the square is 132 m

Area of field = 132×132

= 17424 square metre

Therefore, size of square field is 17424 square metre.