Hole in Expanding Solid

Most recent answer: 02/16/2013

Q:
When a block with a hole in it is heated,why does not the material around the hole expand into the hole and make it small?
- Aqib (age 18)
Karachi,PAK
A:
That's a good question. Intuitively, you might think that when a solid with a hole expands the hole would shrink. However, think of two identical solid blocks with no holes in them. Then, imagine cutting a hole out of one of the solids and heating both blocks and cutout. The regular block will expand and so will the outside of the block with a hole. Also, the cutout will also expand. Because the block with a hole and the cutout together must have the same volume as the solid block, the cutout must fit into hole. Because the cutout expanded, so must the hole. That is why a hole expands when it is heated. I hope this helps.

Erik

(published on 02/16/2013)