When an iron ring is heated the hole becomes larger, smaller, or neither smaller nor larger?

Answer 1

So far 3 people vote for smaller, 4 for larger. I'm for larger. I like apex's example. Also, try a thought experiment. When you heat an iron disc, everyone agrees it expands; every point moves further from the center. Now cut away a smaller, concentric disk, leaving the outer ring. Did you do anything to change how every point moves away from the center? Was the smaller disk pushing the ring outward against its will? Nooo.
Another way of looking at it: A piece of iron wire becomes longer when heated, right? Now join the ends of the wire to make a hoop. The wire will still get longer when heated, so both the inside diameter and the outside diameter increase. Then repeat with thicker wire. Etcetera.

Answer 2

People use this as a logic riddle, but the anser requires knowledge of the mechanical properties of metal, so it's not really a good one.
While logic might tell you the hole would get smaller because the iron expands inward, it really gets larger because the atoms within the ring shift position because of the stresses the expansion causes.

Answer 3

The ABSOLUTELY, GUARANTEED correct answer is LARGER.

When ever an actual press fit ring is heated (such as a ring gear on a flywheel) the inside diameter will easily slip into place over the flywheel - after it cools, it cannot be removed without additional reheating to expand the inside diameter of the hole again or a severe beating with a large hammer.

Answer 4

When heated, an iron ring expands, making the hole larger. Barrel makers used that to advantage by heating iron bands, then forcing them over the barrel staves (side pieces), knowing when the iron cooled, it would compress the staves, making a stonger barrel wall.

Answer 5

Larger. The iron will expand, creating a larger hole.

Answer 6

wouldn't it be smaller because the heat would cause the iron to expand making the hole in the middle smaller. I pictured a donut inflating.

Answer 7

When any object is heated, everything about the object increases in size. The outside of the ring will expand OUTWARDS and the inside of the ring will expand INWARDS. Thus, the hole will become smaller.

Answer 8

larger. Heat expanse.

Answer 9

larger....but you should heat it and then put it on your tounge just too make sure..

Answer 10

i second stephen C.s answer. best answer for him pl0z =P