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Ball in a Hole
Posted 18 May 2007 - 05:31 PM
Posted 08 June 2007 - 02:34 PM
Velcro sticks to tennis balls.
It's a table tennis ball, otherwise known as a ping-pong ball. I have yet to see Velcro stick to an unaltered table tennis ball.
Posted 08 June 2007 - 05:54 PM
Although it was never specified, I believe it to be implied in the original challenge for the pipe to have a sealed bottom and was unable to turned upside down.
I think benjr's right. This would mean that any sucking/vacuum solutions wouldn't work. Creating a vacuum in the pipe (or area of lower pressure approaching a vacuum) would do no good, because you'd just have a closed system in the vacuum+pipe of essentially uniform pressure, which would not move the ball (which I think is supposed to be a ping-pong ball -- table tennis, right?). Even though you're sucking out of one side of the pipe, the air you remove from the pipe is mostly on the wrong side of the ball, so it probably wouldn't move the ball very much, and if it did move the ball at all, gravity never stopped pulling down on the ball, so it would inevitably undo any motion caused by the flow of a little air in the opposite direction.
Also, trying to use a vacuum is different from filling the pipe with water, because buoyancy is a different thing entirely. You could even fill the pipe with a decently heavy gas and the ball should eventually rise to the top, because the solid part of a ping pong ball isn't very dense and on top of that doesn't take up much of its volume.
Posted 11 June 2007 - 09:38 AM
Posted 20 June 2007 - 02:19 PM
Posted 21 June 2007 - 07:51 PM
Posted 22 June 2007 - 02:01 AM
Posted 22 June 2007 - 03:25 AM
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