Question

The echo of a gunshot is heard $8\text{s}$ after the gun is fired. How far from him is the surface that reflects the sound?

Velocity of sound in air $=350\text{m/s}$

• A. $1400\text{m}$
• B. $2800\text{m}$
• C. $700\text{m}$
• D. $350\text{m}$

Answer 1

The correct option is A $1400\text{m}$

Let $d$ is the distance of reflecting surface from the sound source.

So, sound will travel a total distance of $2d$.

Then,

$v=\frac{2d}{t}$

$\Rightarrow 350=\frac{2d}{8}$

$\Rightarrow t=1400\text{m}$

Hence, option $\left(A\right)$ is the correct answer.