<PRE><B>Question 968750</B>
A sound wave has frequency 50 Hz (i.e. it has wavelength (period) = 0.02 seconds). Within each beat, the highest sound intensity is 100 decibel (dB) and the lowest intensity is 60 dB. Supposing that t = 0 corresponds to the low intensity, write down a trigonometric function that describes this sound wave. Sketch the sound wave over two periods.
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Wavelength is distance, not time.
Period = 0.02 seconds
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S(t) = 20*sin(x*2pi/0.02) + 80
Add the phase shift
= {{{20*sin(x*(2pi/.02 ) - (pi/4)/0.02) + 80}}}
= {{{20*sin(x*(100pi) - (pi/4)/0.02) + 80}}}
= {{{20*sin(x*(100pi) - (12.5pi)) + 80}}}

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