A sound wave is given by the following equation:

[tex]\[ y = 6 \sin (324 \pi t) \][/tex]

where [tex]\( t \)[/tex] is time in seconds.

How many cycles will occur between [tex]\( t = 3 \)[/tex] and [tex]\( t = 5.5 \)[/tex] seconds?

[tex]\[ [?] \text{ cycles} \][/tex]



Answer :

Sure, let's walk through this step-by-step!

### Step 1: Understanding the Wave Equation

The given sound wave is defined by the equation:
[tex]\[ y = 6 \sin (324 \pi t) \][/tex]

This is a sine function which represents a sound wave where:
- The amplitude (maximum value of [tex]\( y \)[/tex]) is [tex]\( 6 \)[/tex].
- The angular frequency [tex]\( \omega \)[/tex] is [tex]\( 324 \pi \)[/tex].

### Step 2: Finding the Angular Frequency

The general form of a sine wave is:
[tex]\[ y = A \sin(\omega t) \][/tex]

Here, [tex]\(\omega\)[/tex] (angular frequency) is given as [tex]\( 324 \pi \)[/tex].

### Step 3: Converting Angular Frequency to Regular Frequency

Angular frequency [tex]\(\omega\)[/tex] is related to the regular frequency [tex]\( f \)[/tex] through the formula:
[tex]\[ \omega = 2 \pi f \][/tex]

Given [tex]\(\omega = 324 \pi\)[/tex], we can solve for the frequency [tex]\( f \)[/tex]:

[tex]\[ 324 \pi = 2 \pi f \][/tex]

Dividing both sides by [tex]\( 2 \pi \)[/tex]:

[tex]\[ f = \frac{324 \pi}{2 \pi} = 162 \text{ Hz} \][/tex]

So, the frequency [tex]\( f \)[/tex] is [tex]\( 162 \)[/tex] cycles per second.

### Step 4: Determining the Time Interval

We are given the times [tex]\( t = 3 \)[/tex] seconds and [tex]\( t = 5.5 \)[/tex] seconds. The time interval ([tex]\(\Delta t\)[/tex]) between these two points is:

[tex]\[ \Delta t = t_{\text{end}} - t_{\text{start}} = 5.5 - 3 = 2.5 \text{ seconds} \][/tex]

### Step 5: Calculating the Number of Cycles

The number of cycles that occur within a given time interval can be found by multiplying the frequency by the time interval:

[tex]\[ \text{Number of cycles} = \text{Frequency} \times \Delta t \][/tex]

Substitute the values:

[tex]\[ \text{Number of cycles} = 162 \, \text{Hz} \times 2.5 \, \text{seconds} = 405 \, \text{cycles} \][/tex]

### Final Answer

The number of cycles of the sound wave occurring between [tex]\( t = 3 \)[/tex] seconds and [tex]\( t = 5.5 \)[/tex] seconds is:

[tex]\[ 405 \, \text{cycles} \][/tex]