Question

solve 13th parat....... ....​

Answer 1

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${v}^{2} = {u}^{2} + 2gh$

$= 0 + 2 \times 10 \times 500 = 10000$

$v = \sqrt{10000} = 100$m/s

we also know that v = u + gt = 0 + 10t

100 = 10t or, Time taken by stone to reach the pond surface (t) = 100/10 = 10 sec

therefore, time taken by sound to reach the top from pond surface

➡ d/v = 500/340

➡ 1.47 sec

so the total time taken for splash being heard at the top

➡ 10 + 1.47

➡ 11.47 s

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Answer 2

Since speed of sound in air = 344 m/s

and speed of sound in aluminum = 6420 m/s

we know that v = distance/time therefore time = d/v

time taken by sound wave in air/time taken by sound wave in aluminum

= d/344: d/6420 = 6420/344 = 18.66/1

the sound will take 18.66 times more time through the air than in aluminum in reaching

another boy.

9. The frequency of a source of sound is 100 Hz. How many times does it vibrate in a

minute?

Ans. The frequency of the source of sound bein