Martin Eastburn wrote in news:PUzGv.194874$ne6.53439 @fx09.iad:
No, it won't. Aluminum expands about 12 parts per million per degree Fahrenheit. It would have to be heated to over 800 degrees F to increase the ID by just 1% -- and that's not nearly enough to make the ID as large as the room-temperature OD.
We won't even talk about what that would do to the wooden dowel...
Try linear expansion. around the circle. It is a long ring. A ring will expand more.
Think wagon wheel expanding the wheel band in a fire and then sliding it onto the oak frame of the wheel. cool with water and it fits tight.
one of the experiments in thermo labs is to take a ring and a ball that have the same outsides. Heat both in a flame and the ball slides easily through the ring. Volume is less than linear of the ring.
Martin Eastburn wrote in news:EYAGv.230786$ email@example.com:
No, linear expansion.
No, it will not. The diameter and the circumference increase by exactly the same proportion.
Related thought experiment: suppose you have a string wrapped tightly around the surface of the earth. How much longer does that string need to be, if you want to put it on one-foot-high standoffs all around the planet?
I understand how that works. Do you understand that it's not *at all* the same situation? Fitting a steel band over an oaken wagon wheel requires only that the ID of the band is less than the OD of the wheel at ambient temperature but greater than the OD of the
*wheel* when heated -- *not* that the ID of the band when heated exceeds the OD of the *band* at ambient.
Do the calculations. Assume an aluminum tube with 0.875" OD,
0.050" walls, and therefore 0.775" ID, at 75 deg F. To what temperature must the tube be heated to increase its ID to 0.875"?
On Wednesday, August 13, 2014 6:43:55 AM UTC-4, Doug Miller wrote: ...
... About 8" (two feet / pi).
Related thought experiment: Suppose you have a mile of railroad track. Supp ose it gets really hot and the track expands (in length) by one inch. Suppo se that, due to the expansion, the track buckles in the middle, forming an isosceles triangle. How high will the bump in the middle be?
yeah, well, haven't finished the morning coffee yet. Besides, by the time t hey finished building all those little standoffs, I'd have been paid and sp ent the money. So sue me ;-) And it's all a trick question anyway: EVERYONE knows the earth is flat.
uppose it gets really hot and the track expands (in length) by one inch. Su ppose that, due to the expansion, the track buckles in the middle, forming an isosceles triangle. How high will the bump in the middle be?