Question

A man stand at a distance of $68\mathrm{m}$ from a cliff and fires a gun. After, what time interval will he hear the echo, if the speed of sound in air is $340{\mathrm{ms}}^{-1}$ ?

Answer 1

Step 1: Given data:

Distance from cliff $\left(d\right)$ $=68m$

Speed of sound$\left(v\right)$$=340{\mathrm{ms}}^{-1}$

Step 2: Calculating the time taken:
Total distance covered $=2\mathrm{d}=2\times 68=136\mathrm{m}$
Since the formula for the time taken is given by,
$\text{Time}=\frac{\text{Total distance}}{\text{Speed}}$

Substitute the value in the above equation we get,

$Time=\frac{136}{340}\mathrm{s}=0.4\mathrm{s}\text{.}$

Hence, the time interval is $0.4sec$ after which the echo will be heard.