Do You Know?

[Woody]

Originally Posted By: Redwood

I have a modern convenience called a 'dishwasher'.

That's not a very romantic name for Blanche...

Graeme

She wears many hats.

[ClubV12]

So the answer is: The hole gets bigger, really. The reasoning on this one is a bit confusing though. Because the "metal expands", one could be lead to the conclusion the hole, therefore, would get smaller. It's an excellent question!

[GreatLakesGramma]

I have been giving this some more thought. In a liquid form, molecules are free to move around within the space the substance occupies. But in a solid form, molecules are bonded firmly in place. Thus, for the hole to get smaller, the molecules at the edge of the hole would have to get closer together, the opposite of their behavior when heated.

[True-believer]

I have been giving this some more thought. In a liquid form, molecules are free to move around within the space the substance occupies. But in a solid form, molecules are bonded firmly in place. Thus, for the hole to get smaller, the molecules at the edge of the hole would have to get closer together, the opposite of their behavior when heated.

I don't even know what "Molecules" are???

[GreatLakesGramma]

A molecule is the smallest physical unit of an element or compound, consisting of one or more like atoms in an element and two or more different atoms in a compound.

An atom is the smallest component of an element having the chemical properties of the element, consisting of a nucleus containing combinations of neutrons and protons and one or more electrons bound to the nucleus by electrical attraction.

[Gerr]

Alright, Olger. What's the result of your experiment?

[Gerr]

I have been giving this some more thought. In a liquid form, molecules are free to move around within the space the substance occupies. But in a solid form, molecules are bonded firmly in place. Thus, for the hole to get smaller, the molecules at the edge of the hole would have to get closer together, the opposite of their behavior when heated.

But heat is supposed to make the molecules go FARTHER apart, NOT bunch up closer!

Are we then to suppose that when put in ice, the outer periphery contracts and the inner edge expand thus making the hole bigger?

[GreatLakesGramma]

But heat is supposed to make the molecules go FARTHER apart, NOT bunch up closer!

That is what I said, only in different words. The hole should get larger when heated, smaller when cooled, if the molecules are unable to move from their place relative to each other.

[Bravus]

Just FYI, there are no molecules in a sample of a pure metal, just atoms, held together by metallic bonding.

The rest of the reasoning makes sense.

We all agree that the metal expands and the atoms move further apart as the metal is heated. A plain metal sheet will definitely expand. A metal ring will definitely expand, because the metal all around the edge will expand, making the ring 'longer' and pushing it out to a greater diameter.

The tricky bit here is that, while we all agree that the outside edge of the sheet will expand, making the circumference around the outside edge of the sheet bigger, some of us think this will also make the hole bigger, while others think the metal will also expand 'into' the hole and make it smaller.

Perhaps we're imagining different things? Are we thinking of a square sheet maybe 1 or 2 feet (300-600 mm) along the sides, or of something much smaller or larger? How thick? Are we thinking of a hole half an inch in diameter (12 mm or so, about the diameter of a 5c coin) or a hole that takes up most of the area of the sheet? (I suspect the latter effectively turns the sheet into a ring) Is the hole in the centre or near the edge?

I guess we're waiting on olger's experiments now.

[Bravus]

PS This is fun!

[Amelia]

*GP

Ok, I called and asked poppy this conumdrum. His reply is: the hole will get bigger. If the metal is heated evenly, the hole will expand evenly at the same %rate as the outside area of the metal sheet. When the metal cools the hole will be the same size as it started out. That is unless the metal has been manipulated. The mill my poppy retired from is a rolling mill. Making metal plate. When a customer orders say 3/4" plate, the plate is actually rolled larger to account for shrinkage. And just as an interesting factoid. This mill also makes armor plate for tanks. Your welcome. teehe

[GreatLakesGramma]

Thanks, Amelia. And Bravus, I agree, it's been a fun discussion. I'd still like to see what Olger comes up with - actual measurements and all.

[Amelia]

I wish we could all go to the Mythbusters place and have them do the experiment for us. Wouldn't that be fun???

[Planey]

Taking the sheet similar to the size Bravus suggested (say for arguments sake, 80 cm by 60 cm) Now cut a neat circular piec from near the middle of the sheet (say of diameter 30 cm)

Now lay the sheet on a shelf in a large oven, with the circular disc next to it. Heat them evenly to say 200C.

Now would the disc still fit evenly (exactly) into the hole?

Graeme