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Nick Payne
Joined: 10 Jan 2004
Posts: 2626
Location: Canberra, Australia9/26/17 3:20 AM |
Way OT - interesting sculpture
Came across this on the University of Western Australia campus, outside the Comp Sci building. The granite ball is rotating on a film of water that is being squirted under the ball at an angle to provide both lubrication and the turning effect. The ball is about 30 inches in diameter and so must weigh a fair amount.
Ten seconds of video:
https://photos.app.goo.gl/exNQPtFscmkzet0n2
Cycling content: we were on a bike ride when we came across it.
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Kramer
Joined: 12 Jan 2004
Posts: 121
Location: Richmond, VA9/26/17 6:10 AM |
Science Museum in Richmond, VA
The Science Museum in Richmond, VA has something similar but bigger. They have the moon off to side somewhere (all to scale).
https://www.youtube.com/watch?v=wOnZxNkQeLw
The first earth they had developed a crack and had to be replaced.
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Pat Clancy
Joined: 13 Jan 2004
Posts: 1353
Location: Manchester, CT9/26/17 5:11 PM |
A mathematical challenge!
Assuming your 30" diameter estimate is correct, and assuming the density of granite is 170 lbs per cubic foot (there is a range), the weight is approximately 1,390 lbs.
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PLee
Joined: 08 Dec 2003
Posts: 3713
Location: Brooklyn, NY9/27/17 10:03 AM |
And if you calculate the surface area of the supporting water column, it doesn't take a lot of pressure to support the ball. I'm guessing it's less than 3 psi.
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