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Math Help - Questions related to dv/dt = f(t).

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    Questions related to dv/dt = f(t).

    Last edited by mr fantastic; April 25th 2010 at 08:28 PM. Reason: Re-titled post.
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    Quote Originally Posted by walreinlim88 View Post
    Integrate with respect to t to get v. Integrate v with respect to t to get x.

    Please show what you have done and say where you are stuck if you need more help.
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  3. #3
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    Quote Originally Posted by walreinlim88 View Post
    v = \int{\frac{dv}{dt}\,dt}

     = \int{\sin{(\pi t)} - \sqrt{3}\cos{(\pi t)}\,dt}

     = -\frac{1}{\pi}\cos{(\pi t)} - \frac{\sqrt{3}}{\pi}\sin{(\pi t)} + C_1.


    x = \int{v\,dt}

     = \int{-\frac{1}{\pi}\cos{(\pi t)} - \frac{\sqrt{3}}{\pi}\sin{(\pi t)} + C_1\,dt}

     = -\frac{1}{\pi ^2}\sin{(\pi t)} + \frac{\sqrt{3}}{\pi ^2}\cos{(\pi t)} + C_1 t + C_2.



    Now if you have initial or boundary conditions, use them to find C_1 and C_2.
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    Quote Originally Posted by Prove It View Post
    v = \int{\frac{dv}{dt}\,dt}

     = \int{\sin{(\pi t)} - \sqrt{3}\cos{(\pi t)}\,dt}

     = -\frac{1}{\pi}\cos{(\pi t)} - \frac{\sqrt{3}}{\pi}\sin{(\pi t)} + C_1.


    x = \int{v\,dt}

     = \int{-\frac{1}{\pi}\cos{(\pi t)} - \frac{\sqrt{3}}{\pi}\sin{(\pi t)} + C_1\,dt}

     = -\frac{1}{\pi ^2}\sin{(\pi t)} + \frac{\sqrt{3}}{\pi ^2}\cos{(\pi t)} + C_1 t + C_2.



    Now if you have initial or boundary conditions, use them to find C_1 and C_2.
    may i ask that : start from rest =v=0 when t=0... may u all provide answers 4 me? i actually have done this questions, but i has no confident to my answers, i just want to double check wif u all.. thx...
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    Quote Originally Posted by walreinlim88 View Post
    may i ask that : start from rest =v=0 when t=0... may u all provide answers 4 me? i actually have done this questions, but i has no confident to my answers, i just want to double check wif u all.. thx...
    If that's the case, please post all your working and answers so that it can be reviewed.
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    Quote Originally Posted by mr fantastic View Post
    If that's the case, please post all your working and answers so that it can be reviewed.


    please......help me check...
    is this answers correct?
    thx
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    Quote Originally Posted by walreinlim88 View Post


    please......help me check...
    is this answers correct?
    thx
    I haven't checked every small detail but it looks OK.
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    Quote Originally Posted by mr fantastic View Post
    I haven't checked every small detail but it looks OK.
    help me check every small detail..
    i really not confident at all on my answers..
    thx
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    Quote Originally Posted by mr fantastic View Post
    I haven't checked every small detail but it looks OK.
    plz help me check asapTT ....thx
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  10. #10
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    Quote Originally Posted by walreinlim88 View Post
    plz help me check asapTT ....thx
    I do not check every small detail - maybe someone else has the time. Clearly you know how to do the question so I don't see what your worry is.
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