Question

please answer with detailed solution as fast as you can

Answer 1

Given,
Frequency(f)= 200Hz
Velocity of sound in air(v) = 330m/s
Number of vibrations = 20
Distance =?

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Because the frequency is 200Hz, it indicates that it takes 1 seconds for the sound to complete 200 vibrations.
The question has asked regarding 20 vibrations.
Using above two statements calculate the time required for 20 vibrations to take place.

OK... OK... I'll solve it...

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Simple unitary method, you might be knowing:

200 vibration = 1 second
1 vibration = 1/200 second
20 vibration = (1/200) *20= 20/200= 0.1 second
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Now, what's left in the solution...
We have got the everything needed to calculate the distance that the sound wave will travel.

Time= 0.1 s
Speed = 330m/s

Distance = Speed * Time
= 330 * 0.1
= 33m

So, the correct answer is 33 meters...