Wednesday, November 18, 2009

The Spinning Cylinder Illusion

The Spinning Cylinder Illusion
Donald Simanek | Make Vol. 16- 2008 | Pdf | 3 pgs | 1 mb
I've not been able to track down the origin of
this homemade toy, but it isn't very well known
outside the community of physics teachers. It's
a kinetic illusion, one that depends on physical
motion to make you see something that isn't there.

A familiar example of a kinetic illusion is the
strobe effect sometimes seen in old movies, causing
the spokes of a carriage wheel to seem to be turning
in the wrong direction.

In its simplest form, this toy consists of a hollow
cylinder of rigid plastic. The version in these photos
is 4cm long and 1cm in diameter, with 2mm wall
thickness. It was cut from a piece of polyethylene
plastic tubing that happened to be lying on my
workbench. Whatever tubing you use, be sure to
choose a very straight piece.

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