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5. Priya clapped her hand near a cliff and heard the echo after 2 s. If the speed of
               sound be 330m/s, the distance of the cliff from Priya is
               a.   165 m.

               b.   330 m.

               c.   660 m.

               d.   1320 m


               SUBJECTIVE (BOARD)
               1.  Why  do  we  hear  more  clearly  in  a  room  with  curtains  than  in  a  room  without
               curtains? Explain in brief?

               2. Why Ceiling of good conference halls and concert halls are curved?



               NUMERICALS (BOARD)

               1.  An  echo  is  returned  in  6  seconds.  What  is  the  distance  of  reflecting  surface  from
               source? [Given that speed of sound is 342 m/s]

               2.  A  man  standing  in  front  of  a  mountain  beats  a  drum  at  regular  intervals.  The
               drumming rate is gradually increased and he finds that echo is not heard distinctly
               when the rate becomes 40 per minute. If the velocity of sound is 360 m/sec, then find
               the distance of the mountain from the man? (HOTS)

               3. A man stands at a distance of 25 m from a high wall. He hears the echo off the
               high wall, produced by a clap of his hands. If the velocity of sound is 330 m/s, then
               find the time interval between his original clap and hearing of echo?
               4.  An  observer  standing  in  front  of  a  vertical  wall  claps  10  times  in  one  second.  He
               adjusts his distance from the wall in such a way that the sound of his clapping coincides
               with the echo. This happens when his distance from the wall is 17.5 m. Find the velocity
               of sound as found by him?
























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