This blog is for everyone who uses words.

The ordinary-sized words are for everyone, but the big ones are especially for children.

Monday, 21 April 2014

Spot the frippet: something trochoid.

 Something trochoid moves like this:
File:Cycloid f.gif
animation by Zorgit

(it's the black dot that's trochoid).

If for some reason the animation isn't working on your computer, then a trochoid path is the boing boing boing line followed by a frantic frog.
If you're in Antarctica, where frogs are in short supply, then to see something trochoid all you have to do is stick a bit of chewing gum to the edge of a food can and then roll it along a table.
Neat, huh?
You can do the same thing by rolling a coin marked with eraser fluid, or by attaching a small piece of paper to the side a car tyre. Do be sure to ask the owner of the car, first.
And, whatever you do, don't stick it on with a pin.
Spot the frippet: something trochoid. This word comes from the Greek trokhos, which means wheel.  In this sense trochoid was coined by Gilles de Roberval, who died in 1675.

To make things even easier, anything that can roll or rotate can also be described as trochoid.


  1. Why weren't you my math teacher?
    Your 'boing boing boing' is way may more fun than his 'rolling on a fixed line!'

    1. Perhaps there is something to be said for Maths being taught by someone who has to climb carefully and step by step towards the answer. At least then you've got a chance of seeing how they've got there.