Question

A sound has 13 crests and 15 troughs in 3 seconds. When the second crest is produced the first is 2cm away from the source? Calculate

a. The wavelength

        b. The frequency

        c. The wave speed

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Answer 1

The wavelength will be 4 cm, frequency will be 4.66 Hz and wave speed is 18.6 cm/sec

Step-by-step explanation:

Given:

No. of crest = 13

No. of trough = 15

Time = 3 seconds

Hence, 1 crest or 1 trough =
`(1)/(2)\lambda`

therefore,

13 C + 15 T =
`28((1)/(2)\lambda)`

=
`14\lambda`

Time given 3 seconds

=
`(3)/(14)s`

`\\u= (14)/(3)`

`\\u= 4.6 Hz \approx 5 Hz`

2 cm distance is travelled is time period

`\lambda = 4 cm`

Again wave will travel in 1 T = 4 cm

wave speed v =
`\lambda*\\u`

=
`4*(14)/(3)`

= 18.6 cm/s