Feb 222010
We know that metal expands when heated, so what will happen if you cut a hole the size of a quarter in the center of a cookie sheet, then pop it in the oven until it’s very hot? Will a quarter still fit in the hole? Will the hole be bigger or small and why?
Thanks!
Any shape that is uniformly expanded is uniformly expanded everywhere! That means even the holes themselves “expand”, or become larger, not smaller. This is the reason why machinists frequently use a torch to heat a block of steel to free a dowel, pin, or bolt that might be stuck in it.
To understand why this should be so, imagine I have a complicated shape cut out of a piece of paper. I crisscross it into many tiny squares. Now, I use a copy machine to produce a scaled-up version of it. The shape is exactly the same, but just a bigger version of it. All the tiny squares are still perfectly good squares, but just a bit larger. That’s what happens when matter is heated up and gets bigger. Each little square isn’t paying attention to the rest of the squares around them, all of them just grow in size in the same way.
You’ll have a hot and holy piece of metal.