Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Vector question derivative

  1. Oct 9, 2010 #1
    from this photo its a radius multiplied by sinus wich is aproximated to its angle

    and the divided by dt


    but i dont know how they got the expreesion on the top of the photo

    from the graph on the photo

  2. jcsd
  3. Oct 10, 2010 #2


    User Avatar
    Science Advisor
    Homework Helper

    shalom nhrock3! :smile:

    (btw, we say sine or sin, not sinus :wink:)

    |∆r| is approximately the length of the chord, which is 2r |sin(∆θ/2)|, or approximately 2r(|∆θ|/2), = r|∆θ| :wink:

    and the direction of ∆r is obviously tangential, ie along θ

    so ∆r = r(∆θ) θ
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook