Question

The wavelength of a sound wave is $40cm$ and the time period is $0.0005s$. How many seconds will it take to travel a distance of $4km$?

• A. $5s$
• B. $11s$
• C. $7s$
• D. $16s$

Answer 1

The correct option is A $5s$

Given:
Wavelength of sound wave, $\lambda =40cm=0.4m$
Time period, $T=0.0005s$
Distance travelled, $s=4km=4000m$

Let speed of sound wave be $v$.

Speed of a wave is the product will be:
$v=\frac{\lambda }{T}$
$v=\frac{0.4m}{0.0005s}$
$v=800m{s}^{-1}$

Let the time taken for the wave to travel distance $s$ be $t$.
From definition of speed,
$v=\frac{s}{t}$
$t=\frac{s}{v}$
$t=\frac{4000}{800}=5s$