Monday, May 02, 2011

Pub challenge of the month of the month: Break five toothpicks so that that the two halves are still hinged and then arrange them as spokes on a wheel. Without touching them directly and without using a tool such as a fork, can you get them to rearrange themselves into a five point star? The other stories this month include (a) the physics of a clown car and the general problem of dense packing of objects inside a container and (b) liquefaction in which ground shake turns solid ground into a fluid and allows buildings to slide into the ground.

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Blogger vphd said...

I believe so,

Lay the toothpicks in the configuration shown in the first picture on a paper plate, place the paper plate across two chairs with a gap underneath, and flick upwards with your fingertip in the geometric center of the broken toothpick formation.
Do this with enough force (but not too much force) and you will launch the broken toothpicks into the air, where they will rotate about their center of mass and land in the second configuration.
So long as you do not allow a large enough energy for a high flight, you can ignore the moment of inertia tensor twisting things out of distortion. The star will probably not be perfect, but should still look fairly close to the second configuration.

When I get near some toothpicks (coffee straws?) I will empirically test this out. =)

7:03 PM  

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