Question

calculate the time for which the sensation of sound presists in our brain if the minimum distance of the obstacle from the source of sound is 17.2 metre (speed of sound in air at 344 m
/s)

Answer 1

hi
I am sure you know the formula
t=2d/v
given d =17.2 meter
v =344m/s


t =2*17.2/344
=0.1sec
which is theoretically the minimum time interval to hear a distinct echo

Answer 2

Given that,

The minimum distance of the obstacle from the source of sound is 17.2 metre.

The speed of sound in air is 344 m/s

To find,

The time for which the sensation of sound presists in our brain.

Solution,

The total distance covered by sound during striking and coming bcak is 2d. So,

$v=\dfrac{2d}{t}\\\\t=\dfrac{2d}{v}\\\\t=\dfrac{2\times 17.2}{344}\\\\t=0.1\ s$

So, the time for which the sensation of sound presists in our brain is 0.1 seconds.