Proving the curvature formula for a parametric plane curve

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  • เผยแพร่เมื่อ 21 ธ.ค. 2024

ความคิดเห็น • 26

  • @bprpcalculusbasics
    @bprpcalculusbasics  6 หลายเดือนก่อน +6

    Here's an example of finding the curvature of y=x^2 at (1, 1)
    th-cam.com/video/NUgGbzJcN-s/w-d-xo.html

    • @abacaabaca8131
      @abacaabaca8131 6 หลายเดือนก่อน +1

      Hello Mr, do you have a video about Newton-Raphson method which is one of the ways to get the root of a complicated equation.
      The output does not have to be a number, but it can also be an expression.
      Because the other day I talk to AI how do I convert a single parameter function into a function that relies on two dependent variables.
      This is because I have a Bezier equation which is dependent on parameter t which can also be expressed as f(x,y).
      But to do this it says I need to use Newton-Raphson method which is also an iterative method and is one of the numerical method to find the root of an equation.
      I want to do this, because then I want to apply Green's theorem to find the area of a closed curvature. From there maybe I can find the volume by applying triple integral with parameter z.
      From volume, I can find mass, if I know the density. From, mass I can find force. From force, I can find Power and Work done and also momentum.
      If I know all that I can create a football game. Woo wee. Haha lol.

  • @tobybartels8426
    @tobybartels8426 6 หลายเดือนก่อน +16

    If you leave out the absolute value, the sign tells you which way it's curving, to the right or to the left (as the parameter increases).

  • @algorithminc.8850
    @algorithminc.8850 6 หลายเดือนก่อน +6

    I think these are some of my favorite topics in calculus ... Thanks. Cheers

  • @ianfowler9340
    @ianfowler9340 6 หลายเดือนก่อน +2

    Here's a fun problem I cooked up.
    Find the differential equation that must be satisfied to find the point on y = f(x) where the curvature is a maximum.
    It involves only y ' , y ' ' and y ' ' '. Next, use this DE to find the exact x-value where the curve f(x) = x^3 - 3x reaches maximum curvature. Very cool answer!

  • @mugger8509
    @mugger8509 5 หลายเดือนก่อน

    Thank you so much! This is the only video I could find for this

    • @nathanoher4865
      @nathanoher4865 5 หลายเดือนก่อน

      Same! I always wondered but I feel like I have so many questions that have definitely been answered somewhere… but nowhere that I can access! Until now…

  • @hassankhamis77
    @hassankhamis77 6 หลายเดือนก่อน +1

    I was searching for this ❤

  • @ianfowler9340
    @ianfowler9340 6 หลายเดือนก่อน +5

    Here is a way of developing this formula from scratch - 2D. No vector functions needed. Only basic calculus.
    1) Sketch a general curve in the first Quadrant and label a point P(x,y) on that curve.
    2) Sketch in a tangent line at P and sketch a horizontal line from P to the right. (// x-axis)
    3) You now have defined an angle A between the tangent and the horizontal.
    4) The Curvature at P can be defined the following way: Remember, we are trying to obtain a measure of how "bent" the curve is at P independent of it's orientation.
    As you move along the curve you want to measure how fast A changes per unit of ARC LENGTH. So k = dA/ds. You can use absolute value if you insist on a positive curvature. But negative curvature is O.K. - just indicates concave up or down.
    5) Tools: k = dA/ds
    ds^2 = dx^2 + dy^2 ====> ds/dx = sqrt[ y ' )^2 + 1]
    y ' = tan(A) =====> sec^2(A) = ( y ' )^2 + 1
    dA/dx = [dA/ds)] [ds/dx]
    y ' = tan(A)
    y ' ' = sec^2(A) * dA/dx
    y ' ' = [ (y ' )^2 + 1 ] * [ (dA/ds) * (ds/dx) ]
    Now solve for dA/ds using ds/dx = sqrt[ (y ' )^2 + 1] and you will get:
    k = [y '' ] / [ (y ' )^2 + 1] ^ (3/2)]
    Parametize: x. = dx/dt and y. = dy/dt giving: y ' = y. / x. (Newton's x_dot and y_dot)
    d( y ' )/dt = [ y..*x. - x..*y.] / [ (x.)^2 AND
    d(y ' )/dt = [d(y' )dx]*[dx/dt] = (y '')( *x.)
    Equating, substituting, re-arranging and a little work gives your formula.
    k = [x.y.. - y.x..] / [x.^2 + y.^2]^(3/2)

    • @bprpcalculusbasics
      @bprpcalculusbasics  6 หลายเดือนก่อน +3

      Thank you very much for this wonderful method! And I just recorded a video today too! Thanks.
      th-cam.com/video/kYZCT0XOYuY/w-d-xo.html

    • @ianfowler9340
      @ianfowler9340 6 หลายเดือนก่อน +1

      @@bprpcalculusbasics You are very welcome. Thanks for the shout out. Very nice of you to do that in your new video! Cheers.

  • @jamescollier3
    @jamescollier3 6 หลายเดือนก่อน +7

    That escalated quickly

    • @sebastiangudino9377
      @sebastiangudino9377 6 หลายเดือนก่อน +2

      Can we calculate the curvature to see just how quickly did it escalate?

  • @urluberlu2757
    @urluberlu2757 6 หลายเดือนก่อน +1

    Thank you! 🤩👍

  • @SterlingChaseStubblefield
    @SterlingChaseStubblefield 6 หลายเดือนก่อน +1

    Might be a case where the “dot” notation for derivative is a little cleaner. Love your videos!

  • @Asiago9
    @Asiago9 6 หลายเดือนก่อน +1

    That's a nice new eraser

  • @cdkw2
    @cdkw2 6 หลายเดือนก่อน +1

    That's a curved ball to my brain

  • @fsisrael9224
    @fsisrael9224 6 หลายเดือนก่อน +1

    What field of math is that? Vector calculus?

  • @guilhermerocha2832
    @guilhermerocha2832 6 หลายเดือนก่อน +1

    Amazing. Now do the 3d cruve version hahaha

  • @abacaabaca8131
    @abacaabaca8131 6 หลายเดือนก่อน +1

    If its about geometry I am willing to listen.

  • @Gremriel
    @Gremriel 6 หลายเดือนก่อน +4

    That's a lot of x's and y's.

  • @bernarddoherty4014
    @bernarddoherty4014 6 หลายเดือนก่อน +1

    Holy cow! After “eating’ all of that ‘Math meal’ my mind feels like my belly would feel after eating 2 large pizza’s’ a bucket of KFC chicken and a liter of coke! I don’t have to ‘eat’ anymore math for 2 days,, 😂😂😂😂😩😩😩😳😳

  • @cdkw8254
    @cdkw8254 6 หลายเดือนก่อน +1

    I remember some guy from your Instagram reel saying that if this is math where are the numbers?

    • @Alians0108
      @Alians0108 6 หลายเดือนก่อน +5

      What does numbers have to do with maths though?

    • @windowsxpmemesandstufflol
      @windowsxpmemesandstufflol 6 หลายเดือนก่อน +1

      numbers are only for computation and calculation?