PI

Discussion in 'Math' started by lomax1, Feb 18, 2014.

  1. lomax1

    Thread Starter New Member

    Feb 6, 2014
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    I HAVE HAD THIS THROWN, KICKED AND EVEN SPAT AT ME BUT DOES NOT SEEM TO GO IN....

    ∏ (pi) if I have an equation 2∏t does this mean 2 of that number or 2 halves? so confused....
     
  2. MrChips

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    Oct 2, 2009
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    It usually means two times pi times t

    2 x ∏ x t

    where ∏ = 3.141592653589793

    Give us the context so we can better help you.
     
  3. lomax1

    Thread Starter New Member

    Feb 6, 2014
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    (2∏t)
    T
     
  4. MrChips

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    Oct 2, 2009
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    Nice.

    Usually T refers to the period of a repetitive signal
    and t is a time variable.

    Hence

    t/T x 2∏

    refers to the phase angle at time t where the phase angle is calculated in radians.

    (There are 2∏ radians in 360 degrees or one period.)
     
  5. lomax1

    Thread Starter New Member

    Feb 6, 2014
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    Great stuff, so 2∏50 = 100 ?
    50 50
     
  6. shteii01

    AAC Fanatic!

    Feb 19, 2010
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    2*pi*50/50=2*pi=2*3.14=6.28

    100/50=2
     
  7. MrChips

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    What?.......
     
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  8. lomax1

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    Feb 6, 2014
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    sorry, 2∏50/50 = 100/50
     
  9. shteii01

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    6.28 is not equal 2
     
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  10. MrChips

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    Oct 2, 2009
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    No.

    ∏ has a value 3.141592654589793

    You have to multiply 100/50 by 3.141592654589793

    50/50 x 2 x pi = 2 ∏ radians = 360 degrees
     
  11. t_n_k

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    Mar 6, 2009
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    Is this a novel method of teaching?
     
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  12. lomax1

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    Feb 6, 2014
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    So then, t= 0.002 Seconds, T(Tau)= 1.6 Seconds, T = 50 milliseconds and the equation is : y(t)=e-t/t(tau)sin(2∏t/T) It would be written as: e-0.002/1.6sin(2x50/∏)?
     
  13. MrChips

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    Oct 2, 2009
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    No.

    sin(2 pi t/T) = sin( 2 x 3.14159 x 0.002 / 0.050)
     
  14. lomax1

    Thread Starter New Member

    Feb 6, 2014
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    o...k, and the first bit before the sin is ok?
     
  15. shteii01

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    Feb 19, 2010
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    Yes, it looks alright, the t is in seconds, the tau is in seconds. So you have: e to the power of -t/Tau
    e^{\frac{-t}{Tau}}=2.71^{\frac{-0.002}{1.6}}=0.998
    I think you can round it up to 1 or just keep 0.998 or 0.99
     
  16. WBahn

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    Mar 31, 2012
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    Notice that you have

    y(t)=e-t/t(tau)sin(2∏t/T)

    This is very ill-formed. Strictly speaking, what you have written is

    <br />
y(t) \; = \; e\,-\, \( \frac{t}{t} \) \tau \, \sin \( \frac{2 \pi t}{T} \)<br />

    What I'm pretty sure you meant to write is

    <br />
y(t) \; = \; e^{- \frac{t}{\tau}} \, \sin \( \frac{2 \pi t}{T} \)<br />

    which, in text, would be written as

    y(t) = e^(- t/tau ) * sin(2∏t/T)
     
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