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anonymous

  • one year ago

A sound wave is modeled with the equation y= 1/4 cos 2pi/3 theta . a. Find the period. Explain your method. b. Find the amplitude. Explain your method. c. What is the equation of the midline? What does it represent?

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  1. anonymous
    • one year ago
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    |dw:1444621224019:dw|

  2. kropot72
    • one year ago
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    Consider the following equation: \[\large y=A cosB \theta\] The amplitude is |A|. The period T is \[\large T=\frac{2 \pi}{B}\]

  3. anonymous
    • one year ago
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    so time period = 2pi/3

  4. kropot72
    • one year ago
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    Substituting 2pi/3 for B we get \[\large T=\frac{2 \pi}{\frac{2 \pi}{3}}=you\ can\ calculate\]

  5. anonymous
    • one year ago
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    how would i do that

  6. kropot72
    • one year ago
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    \[\large T=\frac{2 \pi \times3}{2 \pi}=?\]

  7. anonymous
    • one year ago
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    well 2 pi can cancel eachother out right

  8. kropot72
    • one year ago
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    Yes, your cancelling idea is correct.

  9. anonymous
    • one year ago
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    so would it be t= 3/2pi

  10. kropot72
    • one year ago
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    |dw:1444614205373:dw|

  11. anonymous
    • one year ago
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    t=3

  12. kropot72
    • one year ago
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    Correct.

  13. anonymous
    • one year ago
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    i dont quite understand what answers to a b and c would really be. I understand what we did. I guess i just dont understand what they are asking

  14. anonymous
    • one year ago
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    would amplitude be 1/4

  15. anonymous
    • one year ago
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    and by period do they mean time? if so then that cannot be determined

  16. kropot72
    • one year ago
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    You now have the answer to a and the method for finding the period. The time is in seconds. I have shown you how to find the amplitude, it is |A| in the general equation that I gave you. Yes, the amplitude is 1/4 unit. The equation of the mid line is simply: y = 0.

  17. kropot72
    • one year ago
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    The maximum value of the cos function is 1, and the minimum value of the cos function is -1. That is why the equation of the mid line is y = 0.

  18. anonymous
    • one year ago
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    How do I find the period? 2pi and 1/4?

  19. kropot72
    • one year ago
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    The period T was calculated to be 3 seconds.

  20. anonymous
    • one year ago
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    how did we get that?

  21. kropot72
    • one year ago
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    We substituted 2pi/3 for B is the equation \[\large T=\frac{2 \pi}{B}=\frac{2 \pi}{\frac{2 \pi}{3}}=\frac{2 \pi \times3}{2\pi}=3s\]

  22. anonymous
    • one year ago
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    ohhhh okay! I see how that would be the answer thank you!

  23. kropot72
    • one year ago
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    You're welcome :)

  24. anonymous
    • one year ago
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    i just have one question that im kinda confused about, if i did it right. coul you look at it and tell me if I have the right idea

  25. kropot72
    • one year ago
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    Please post your next question as a new question. Thank you.

  26. anonymous
    • one year ago
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    alright:)

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