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Cool goIITian

Joined:	24 Jul 2009
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24 Jul 2009 21:44:37 IST

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a boy and girl stand 200m apart beside a long metal fence on a still day . the girl places her ear a

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a boy and girl stand 200m apart beside a long metal fence on a still day . the girl places her ear against the fence with a hammer .Two sounds separated by time interval of 0.5s are heard by girl .if velocity of sound in air is 340m/s,find the velocity of sound in metal?

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Killer Kiran

Blazing goIITian

Joined: 6 Aug 2007

Posts: 1860

24 Jul 2009 21:49:06 IST

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Velocity of sound in air is 340m/s

It has travelled 200 m so it takes time of .588 second..

We know that speed of sound in metal is more than that of air

so the time taken by sound to travel in metal shud be .088 second..

so that gives us a velocity of 2272 m/s ..

correct me if i am wrong..

edison

Forum Expert

Joined: 19 Oct 2006

Posts: 7537

8 Mar 2010 10:44:18 IST

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Let velocity of sound in metal fence = u

velocity of sound in air = 340m/s

Distance traveled by sound in either cases = 200 m

Now time taken by sound to travel in metal = 200/u seconds

Time taken by sound to travel in air = 200/340 seconds

Obviously the velocity of sound is greater in metal fence.

Thus,

200/u + 0.5 = 200/340

or u = 2266.66 m/s

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