Question

An object makes 20 vibrations in 20 seconds. Calculate the following for the vibration of the object
a) Frequency b) Time period
Will the sound produced by the object be audible to the human ear? Give reasons.

Answer 1

Answer:

a)20hz

b)20sec

Yes, it will be heard by human because humans can hear between 20hz to 40hz

Answer 2

Solution -

As per the question , An object makes 20 vibrations every 20 seconds .

Hence number of vibrations per second is 20/20 = 1 .

The object makes one vibration or completes 1 cycle in each second. Hence , the frequency of the object becomes 1 (vibrations/sec) .

As for the time period , t = 1/frequency = 1 second .

The sound produced by this object will not be audible to the human ear. The human ear can only recognise sounds lying between the frequencies of 20Hz to 20 kHz .

Below 20 hz it becomes infrasonic sound and above 20khz it's ultrasonic sound. The sound produced by this object is infrasonic .

Answer - (a) Frequency is 1 Hz

(b) Time period is 1 second .

(c) No, it will not be audible to the human ear.

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