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Q & A: thermal expansion of holes

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Most recent answer: 10/22/2007
Q:
If I heat uniformly a large cube of concrete with a small spherical hole in the middle, will the radius of the hole get larger or smaller? If the side of the block increases by 4%, what % will the radius of the hole change? What if the cube is made of asphalt?
- Dougal (age 57)
San Marino, CA
A:
There’s a very simple solution here. These materials are uniform on a large scale, even though they’re lumpy on a small scale. So when they heat up and expand, all the dimensions expand together by the same %. This uniform expansion obviously lets each part expand by the same amount in every direction. That includes the dimensions of any holes.

Mike W.

(published on 10/22/2007)

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