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प्रश्न
A man standing 825 metres away from a cliff (steep rock) fires a gun. After how long will he hear its echo ? Speed of sound in air is 330 m/s.
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उत्तर
We have to calculate time taken by the sound wave to reach the reflecting surface.
Given: Distance between the observer and reflecting surface d = 825 m
Velocity of sound ν = 330 m/s
We know the time taken by sound wave to reach the reflecting surface is,
t = 2d/ν
⇒ t = (2)(825)/330
⇒ t = 5 s
This is the required time.
संबंधित प्रश्न
What is meant by an echo?
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What is the minimum distance in air required from a sound reflecting surface to hear an echo (at 20°C) ?
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Which of the following device does not work on the multiple reflections of sound waves ?
Explain by giving a scientific reason.
We cannot hear the echo produced in a classroom.
Answer the following question in your own words.
What is an echo?
What is the minimum distance needed for an echo?
State two conditions necessary for hearing an echo.
What are the medical applications of echo?
To hear an echo, the minimum distance of the obstacle from the source of sound must be ______.
What is an echo? Write the conditions to hear an echo.
Numerical problems:
An echo returned in 3s. What is the distance of the reflecting surface from the source given that the speed of sound is 330 ms-1?
Rohan conducted experiments on echo in different media. He observed that a minimum distance of 'x' meters is required for the echo to be heard in oxygen and 'y' meters in benzene. Compare 'x' and 'y'. Justify your answer.
Speed of sound in oxygen: 340 ms-1
Speed of sound in benzene: 200 ms-1
