Welcome to your Ncert – class 9- science – Chapter 11 – Sound 2
An echo is heard because of the persistence of _____________
Three different vibrating bodies produce three types of sounds X, Y, and Z.
The minimum distance between the source of the sound and the obstacle for an echo (at 20ºC) to take place is :
The loudness of sound decreases with an:
A man pronounces a, b, c, d and e and hears last four syllables as an echo. Taking velocity of sound as 340 ms-1 , the distance of reflecting surface, if it takes one-fifth of a second to pronounce or hear one syllable is
When a tuning fork is striked using a rubber prong, the compressions and rarefactions in the sound wave correspond to
An underwater sonar source operating at a frequency of
The time period of a vibrating body is 0.02s. The frequency of the vibrating body will be
A person is in front of a vertical mountain fires a bullet and hears its echo after a time 3 s. The person walks a distance 'd' towards mountain then fires another bullet and hears its echo after a time 2 s. If velocity of sound in air is 340 ms-1 , the value of 'd' is
The time period of the second hand in a clock is :
Identify the longitudinal waves from the following
Which of the following is/are correct statement(s)?
When a tuning fork produces sound waves in air, which one of the following is the same in the material of tuning fork as well as in air ?
A person standing between a pair of tall and wide cliffs claps his hands. He hears the first two echoes at 2 sec and 3 sec respectively. If the speed of sound is 330 m/sec, then
Which one of the following material will reflect sound better?
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