$A$ car is moving with a speed of $72 \,km/h$ towards a hill. The car blows its horn at a distance of $1800 \,m$ from the hill. If the echo is heard after $10 \,s$,the speed of sound (in $m/s$) is:

$A$ firecracker exploding on the surface of a lake is heard as two sounds a time interval $t$ apart by a man on a boat close to the water surface. Sound travels with a speed $u$ in water and a speed $v$ in air. The distance from the exploding firecracker to the boat is

$A$ stone is dropped into a well that is $19.6\,m$ deep. If the echo is heard after $2.06\,s$ of dropping the stone,calculate the velocity of sound in $m/s$.

The velocities of sound at the same pressure in two monatomic gases of densities ${\rho _1}$ and ${\rho _2}$ are $v_1$ and $v_2$ respectively. If ${\rho _1}/{\rho _2} = 2$,then the value of $\frac{{{v_1}}}{{{v_2}}}$ is:

Which of the following statements is correct?

$A$ sound wave is travelling with a frequency of $50 \,Hz$. The phase difference between two points in the path of the wave is $\frac{\pi}{3} \,rad$. The distance between those two points is (Velocity of sound in air $=330 \,m/s$) (in $m$)