Sound (Numerical)

What should be the minimum distance between source and reflector in water so that echo is heard distinctly?
(The speed of sound in water = 1400 m s^-1)

A pendulum has a frequency of 5 vibrations per second. An observer starts the pendulum and fires a gun simultaneously. He hears echo from the cliff after 8 vibrations of the pendulum. If the velocity of sound in air is 340 ms^-1, find the distance between the cliff and the observer.

A boy standing in front of a wall at a distance 17 m produces 10 claps per second. He notices that the sound of his clapping coincides with the echo. Echo is heard only once when clapping is stopped. Calculate the speed of sound.

The smoke from the gun barrel is seen 2 seconds before the explosion is heard. If the speed of sound in air is 340 ms⁻¹, calculate the distance of the observer from the gun. State the approximation used.

A man standing 48 m away from a wall fires a gun. Calculate the time after which an echo is heard. (The speed of sound in air is 320 ms^-1).

A person standing between the two vertical cliffs produces a sound. Two successive echoes are heard at 4 s and 6 s. Calculate the distance between the cliffs.
(Speed of sound in air = 320 ms^-1)

A man standing 25 m away from a wall produces a sound and receives the reflected sound.

1. Calculate the time after which he receives the reflected sound if the speed of the sound in air is 350 m/s^-1.
2. Will the man be able to hear a distinct echo? Explain the answer.

A person fires a gun while standing at a distance of 850 m from a building. If the speed of sound is 350 ms, calculate the time in which the person hears an echo of the gun flte.