Question

A sound has a frequency of $1,000\text{Hz}$ and a wavelength of $34\text{cm}$. How long will it take to travel $1\text{km}$?

• A. $4.94\text{s}$
• B. $3.94\text{s}$
• C. $1.94\text{s}$
• D. $2.94\text{s}$

Answer 1

The correct option is D $2.94\text{s}$

We have,
$\nu =1000\text{Hz}$
and
$\lambda =34\text{cm}=\frac{34}{100}\text{m}.$
The wave speed is $v=\nu \lambda =\left(1000s^{-1}\right)\left(\frac{34}{100}\text{m}\right)=340\text{m/s}$
The time taken by the wave to travel 1 km is
$t=\frac{s}{v}=\frac{1\text{km}}{340\text{m/s}}=\frac{1000\text{m}}{340\text{m/s}}=2.94\text{s}.$