A circle made of points, shown here with small white balls, appears to roll around the inside edge of a larger circle, but is that what’s really happening? File under: Cycloids, hypocycloids, and optical illusions. This mechanical gear design, demonstrated by the Visual Education Project and originally developed by Italian polymath Girolamo Cardano (1501-1576), demonstrates how circular motion can result from linear motion.
Cycloid illusion: Are these dots really moving in a circle?
“Copernicus’ Theorem states a surprising result that a point on the circumference of the small circle traces a straight line segment – a diameter of the big circle, to be precise…
“Cardano’s work with hypocycloids led him to the Cardan joint or gear mechanism, in which a pair of gears with the smaller being one-half the size of the larger gear is used converting rotational motion to linear motion.”
Plus, more math videos, including:
• Types of Triangles
• Mathematica – A World of Numbers… and Beyond
• Professor Kokichi Sugihara creates his mind-blowing illusions with math
• How High Can You Count on Your Fingers?
• How Many Ways Are There to Prove the Pythagorean Theorem?
Bonus: Spirograph pancakes.
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