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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
Does sound follow the same laws of reflection as light does? Explain.
When a sound is reflected from a distant object, an echo is produced. Let the distance between the reflecting surface and the source of sound production remains the same. Do you hear echo sound on a hotter day?
Which of the following statement best describes frequency?
Name the device which is used to address a small gathering of people.
In which medium, air or water, an echo is heard much sooner ? Why ?
Why do we hear more clearly in a room with curtains than in a room without curtains ?
Why are the ceilings of concert halls made curved ? Draw a labelled diagram to illustrate your answer.
Name any two objects which are good reflectors of sound.
What is an echo ? How is echo formed ?
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.
State two conditions necessary for hearing an echo.
How can you calculate the speed of sound using echo?
______ is an image obtained by the use of reflected ultrasonic waves.
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?
Answer the following question in your own words.
What factors are important to get a distinct echo?
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
