Welcome to the College Mathline Blog

This blog accompanies the College Mathline television program produced by Palomar College

Here you can post a question for us or a comment about the show. You can also find information on our "real world" applications of mathematics.

Wednesday, April 30, 2008

The Cycloid


A cycloid is the curve formed by a fixed point on the edge of a wheel as the wheel rotates along the ground. The curve is given by the parametric equations
x = r (t - sin t),
y = r (1 - cos t)
where r is the radius of the wheel. If you take one arch of the graph and turn it upside down it forms a ramp with a special property: it is the fastest path for a ball rolling down from one point to another. A second interesting fact: if you do have a ramp in this shape, no matter where you start a ball rolling, it will always take the same amount of time to reach the bottom. The cool photo is from illum on Flickr.

Note that our contest is still open!

Related links:

Wikipedia entry for cycloid

YouTube video of a marble rolling down a cycloid ramp

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