Mechanics
Uphill Cone - Defying Gravity?
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This double cone appears to do the impossible: it rolls uphill by itself.
Is gravity being defeated, or is something else happening?
Look carefully at the shape of the cone and the way the rails change as they spread apart.
Watch the centre of the cone, not just the points touching the rails. Is the whole object really rising?
Additional Information
The illusion comes from the rails spreading apart as they rise, letting the cone’s widening body sink lower even as its visible position climbs.
The cone’s center of gravity is always moving downward, obeying gravity exactly as expected — only the outer shape’s position looks like it’s defying it.
This classic demonstration has been used to teach center-of-mass thinking for centuries.