91Ó°ÊÓ

The number of vibrations per second is how frequency is defined. Wavelength is the shortest distance over which a wave can recur. The velocity of a wave is its speed over a certain period of time.

The speed of the wave is given by

_{$\mathrm{v}=\frac{\mathrm{λ}}{\mathrm{T}}$}

Where,$\mathrm{λ}$is the wavelength of the wave, v is the speed of sound. T is the time period of wave.

The distance between one wave crest to another crest is $\mathrm{λ}=800\mathrm{km}$

The time required to complete waves is$\mathrm{T}=1.0\mathrm{hour}$

Formula to calculate the speed of the wave is

_{$\mathrm{v}=\frac{\mathrm{λ}}{\mathrm{T}}$}

Substitute 800 km for $\mathrm{λ}$and 1.0 hour for T in the above equation.

_{$$\begin{gathered} \mathrm{v}=\frac{800\mathrm{km}\left({\displaystyle \frac{{10}^3\mathrm{m}}{1\mathrm{km}}}\right)}{1.0\mathrm{hr}\left({\displaystyle \frac{3600\mathrm{s}}{1\mathrm{hr}}}\right)} \\ =222.2\mathrm{m}/\mathrm{s} \end{gathered}$$}

Convert the speed in m/s as,

_{$$\begin{gathered} \mathrm{v}=\left(222.2\mathrm{m}/\mathrm{s}\right)\left(\frac{1\mathrm{km}}{{10}^3\mathrm{m}}\right)\left(\frac{3600\mathrm{s}}{1\mathrm{hr}}\right) \\ =799.9\mathrm{km}/\mathrm{hr} \end{gathered}$$}

Hence, the speed of sound wave in m/s is 222.2 m/s and in km/hr is 799.9 km/hr