A pendulum has a frequency of 5 vibrations per second. An observer starts the pendulam and fires a gun simultaneously. He hears an eco from the cliff after 8 vibrations of the pendulum. Find the distance between the cliff and the observer. (Velocity of the sound in the air= 340m/s)
Answers
Answer:
A pendulum has a frequency of
An observer starts the pendulum and fires simultaneously and he hears the echo from a cliff after 8 vibrations of the pendulum
Explanation:
Answer:
The sensation of any sound persists in our ear for about 0.1 seconds. This is known as the persistence of hearing. If the echo is heard within this time interval, the original sound and its echo cannot be distinguished. So the most important condition for hearing an echo is that the reflected sound should reach the ear only after a lapse of at least 0.1 second after the original sound dies off.
It is given that a pendulum has a frequency of 5 vibrations per second. An observer starts the pendulum and fire a gun
simultaneously. He hears echo from the cliff after 8 vibrations of the pendulum which means that he hears the echo after 1.6 seconds. The speed of sound is given as 340m/s.
The distance traveled by sound of the gun shot in 1.6 seconds is calculated from the formula
Distance traveled =velocityofsound×timetaken. That is, 340×1.6 = 544 m. This is twice the minimum distance between a source of sound (man) and the reflector (cliff) as it is reflected sound.
So, the cliff is at a distance of 272 m least from the man, for the reflected sound or the echo to be heard distinctly in 1.6 seconds.
Explanation: