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

Homework Help: Cardoid issue

  1. Sep 14, 2010 #1
    A wheel radius a rolls along a line without slipping. The curve traced by a point P that is b units from the center (b < a) is called a curtate cycloid (see figure). Use the angle θ to find a set of parametric equations for this curve.

    I went through the book, went to the math lab at my university, and still I cannot find the right solution. I had


    but my tutor just said to replace a and b. I tried that on webassign and still, I received a red mark wrong! I could use some help if anyone could spare any? Thank you all :smile:

    Attached Files:

  2. jcsd
  3. Sep 14, 2010 #2


    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    Of course, your answer can't be correct because it doesn't involve b.

    Try thinking of the position vector of the moving point of radius b as the sum of two vectors. The first is the vector from the origin to the center of the circle. The x and y components of that vector only involve a. Then think of the vector from the center of the circle of radius b and angle theta. Write its components in terms of b and theta. Then add the two vectors up.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook