What happens to holes?

When an object is heated and expands, what happens to any holes in the object? Do they get larger or smaller?

  1. the holes get smaller
  2. the holes stay the same size
  3. the holes get larger

The holes expand as if they were made from the same material as the object. An easy way to see why is to take two flat pieces of metal. Draw circles of the same size on both, and cut out one of the circles to make a hole. Heat them both. The object that is still intact, which has a circle drawn on it, will expand, making the drawn circle larger. The other object, with the hole, matches what the first object does, so its hole also expands.