Metal Expansion Rates ```Name: maria c paoletti Status: N/A Age: N/A Location: N/A Country: N/A Date: Around 1993 ``` Question: I am doing a science fair project on the expansion rates of three different metals: copper, aluminum and galvanized steel. I was trying to make a hypothesis but I could not find any information on how much these metals expand. Can anyone help me find some information? Also, I got some wire made of the given metals and I would like to know if a home electric oven would make a very noticeable change when the wire expands. The wire is 18 gauge. Replies: I assume that the expansion rates that you are asking about are thermal expansion rates, in other words, the change in length per degree of tempera- ture. The valuer for metals are around 10 x 10^-6 per degree centigrade or about one thousandth of a percent change per degree. You can find the exact numbers in a book called the Handbook of Chemistry and Physics, which your public library should have. Finding a number for galvanized steel will be hard, especially if you do not know the type of steel or the thickness of the coating. But that is what makes this an interesting experiment! In your home oven, you might be able to raise the temperature by about two hundred or two hundred fifty degrees centigrade. That will give you a length change of about a quarter or fifth of a percent. That would be less than a thirty second for an inch on a ten inch piece for wire. That is possible, but you will have to be either very careful or clever. (Hint: Does the wire have to be straight?) I hope your experiment works out well. edward p barth Click here to return to the Engineering Archives

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