Curious case of the mystery top (i)

The tippe top toy is one of the great mysteries of science. As you see below, when it is set to spin with sufficient angular velocity, the top turns itself over and spins on its stem for a while until friction slows it down.

Suppose we draw an arrow on the upright tippe top, pointing counterclockwise, as so

If we spin the top counterclockwise (in the direction of the arrow), what will happen when the tippe top turns over to spin on its stem?

The arrow will point in the spin direction in most, but not all attempts The arrow will point against the direction of spin The top has equal probability to end up spinning in either direction The arrow will continue to point in the direction of spin

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3 solutions

Manoj Pillai
Jul 21, 2014

The arrow is drawn to point counter-clockwise. In the initial spin (before flipping) the arrow points in the direction of the spin, as the imparted spin is counter-clockwise too. Finally when it flips over, the direction of spin is maintained by the top. But due to the flip the arrow's head will be pointing away from the direction of the spin. Ergo the arrow points away from the direction of the spin.

Good one. You got me.

Michael Horton - 6 years, 10 months ago

Poorly worded question in my opinion.

Cody Gammon - 4 years, 10 months ago

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Exactly. They claimed to draw the arrow ON the toy.

Nicole Baumchen - 3 years, 4 months ago
Chew-Seong Cheong
Jul 25, 2014

The direction of rotation relative to the tippe toy does not change due to conservation of momentum. When the top tips over, to the observer the direction of rotation changes. Seeing it from the top it changes from counterclockwise to clockwise.

thank you, I agree, poorly worded.

Cody Gammon - 4 years, 10 months ago
Kinshu Kr.
Jul 27, 2014

The arrow after flipping remains in the same direction if watched from below. But as our reference frame is from the top is moves in the clockwise direction. Hence pointer will against the dir. of spin.Cheers!

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