A child hears an echo from a cliff 4 seconds after the sound from a powerful cracker is produced. How far away is the cliff from the child? Velocity of sound in air at `20^@ C `is 344 m/s :

A submarine emits a sonar pulse, which returns from underwater cliff in 1.02 s. If the speed of sound in salt water is 1531ms^-1 how far away is the cliff ?

A stone is dropped from the top of a tall cliff and n seconds later another stone is thrown vertically downwards with a velocity u m/s. How far below the top of the cliff the second stone will overtake the first?

A message was transmitted from boat which returned to the sender after reflection from the bottom of the sea in 0.8 s. If the velocity of sound in water is 1500ms^-1 then find the depth of sea.

A SONAR (sound navigation and ranging) uses ultrasonic waves to detect and locate objects under water. In a submarine equipped with a SONAR the time delay between generation of a probe wave and the reception of its echo after reflection from an enemy submarine is found to be 77.0 s. What is the distance of the enemy submarine? (Speed of sound in water = 1450 m s^-1 ).

A person has a hearing range from 20 Hz to 20 KHz. What is the typical wavelength of sound waves in air corresponding to these frequencies ? Take the speed of sound in air as 344 ms^ -1 .