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Math Help - sinusoidal function

  1. #1
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    sinusoidal function

    need help with this can you provide any light on it.....

    The instantaneous value of current, i amp, at t seconds is given by

    i= 15 sin (100 pi t + 0.6)

    Find
    the amplitude
    the period
    the frequency
    the initial phase angle when t =0 expressed in both radians and degrees
    the value of i when t=2.5
    the time in milliseconds when the current first reaches its maximum value

    I need all the help I can get thanks
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  2. #2
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    Re: sinusoidal function

    For y = A \sin B (x-C)

    A is the amplitude and \frac{2\pi}{B} is the period, can you answer the first two now?
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  3. #3
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    Re: sinusoidal function

    no sorry can you help some more
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  4. #4
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    Re: sinusoidal function

    Quote Originally Posted by gordonmckee View Post
    no sorry can you help some more
    you really need to research how sinusoidal graphs are transformed ...

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  5. #5
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    Re: sinusoidal function

    Amplitude ---- 15

    Period ---- 2 pi / 100 pi = 1/50

    Frequency ---- F=1 / (1/50) = 50Hz

    Phase Angle ---- 0.6 rad = (0.6 x (180/pi)) = 34.38deg or 34o 23' leading

    I ----15 sin (100 pi 2.5 + 0.6) = 15 sin (786) = 15 x 0.9063 = 13.59Amps

    Time ---- 15 = 15 sin (100 pi t + 0.6)

    arcsin 15 / 15 = ( 100 pi t + 0.6)

    90o or 1.5708rad

    100 pi t = 1.5708 - 0.6

    t = 0.9708 / 100 pi

    t = 0.0031

    = 3.1 ms

    Am I way off the mark here can someone advise please?
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  6. #6
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    Re: sinusoidal function

    can anyone varify if i'm right on this or not
    Thanks
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  7. #7
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    Re: sinusoidal function

    I take it I am on the right track with this then.....
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  8. #8
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    Re: sinusoidal function

    is it nobody knows or not wanting to say that im wrong....please help
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  9. #9
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    Re: sinusoidal function

    Quote Originally Posted by gordonmckee View Post
    is it nobody knows or not wanting to say that im wrong....please help
    I think your on the right lines, I have just completed this question for my HNC and I have the same answers which I confirmed with my tutor today

    Are you at Teeside University?
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