Which of the following frequencies of sound waves is audible to human beings?

How does the speed of a sound wave depend on the absolute temperature of air?

$A$ 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

Speed of sound at constant temperature depends on

Newton assumed that sound propagation in a gas takes place under which condition?

At what temperature will the speed of sound be nearly $1.5$ times its value at $N.T.P.$ (in $^{\circ} C$)?