An engine approaches a hill with a constant speed. When it is at a distance of $0.9 \, km$,it blows a whistle whose echo is heard by the driver after $5 \, s$. If the speed of sound in air is $330 \, m/s$,then the speed of the engine is .... $m/s$.

Match Column - $A$ with Column - $B$.

Column - $A$	Column - $B$
$(a)$ Speed of longitudinal waves in gas and liquid.	$(i)$ $v = \sqrt{\frac{B}{\rho}}$
$(b)$ Speed of longitudinal waves in solid rod.	$(ii)$ $v = \sqrt{\frac{Y}{\rho}}$
$(c)$ Speed of sound in air according to Newton.	$(iii)$ $v = \sqrt{\frac{P}{\rho}}$
$(d)$ Speed of sound in air according to Laplace.	$(iv)$ $v = \sqrt{\frac{\gamma P}{\rho}}$

If the density of oxygen is $16$ times that of hydrogen,what will be the ratio of their corresponding velocities of sound waves?

$A$ sound wave of frequency $v \text{ Hz}$ initially travels a distance of $1 \text{ km}$ in air. Then,it gets reflected into a water reservoir of depth $600 \text{ m}$. The frequency of the wave at the bottom of the reservoir is $(V_{\text{air}} = 340 \text{ m/s}, V_{\text{water}} = 1484 \text{ m/s})$

When sound waves travel from air to water,which of the following remains constant?

$A$ tuning fork of frequency $220 \,Hz$ produces sound waves of wavelength $1.5 \,m$ in air at $N.T.P$. The increase in wavelength when the temperature of air is $27^{\circ} C$ is nearly $\left(\sqrt{\frac{300}{273}}=1.05\right)$ (in $\,m$)