Calculating Thermal Expansion of a Cookware Pot

[n.hirsch1]

Homework Statement

Some cookware has a stainless steel interior (alpha = 17.3 *10^- 6) and a copper bottom (alpha = 17.0 * 10^-6) for better heat distribution. Suppose an 8.0 in. pot of this construction is heated to 620 C on the stove.

Homework Equations

Delta L = alpha* Lo * delta T

The Attempt at a Solution

I used the definition of coefficient of linear expansion to find the change in diameter for both copper and stainless steel. For stainless steel I found 0.083 inches, and for copper I found 0.0812 inches. I don't know where I am supposed to go from here, this is a homework problem online, and neither of the above answers nor their difference is the correct answer.
Please help!

 

[kuruman]

I don't know where you are supposed to go from here either. You say your answer is incorrect, but you are not saying what the question is. Also, it would help if you showed exactly what you did. Giving a wrong answer is not enough to find where you might have gone wrong.

 

[n.hirsch1]

Sorry! I forgot the second part:
If the initial temperature of the pot is 23 C, what is the difference in diameter change for the copper and the steel?

All I did was plug in the numbers for the coefficient of linear expansion,
For stainless steel: L = (17.3 * 10^-6) * (8 in) * (620 C - 23 C) = 0.083
and the same method for copper, so L = 0.0812

 

[kuruman]

You are looking for the difference between the changes. That's the difference in diameter change that the problem is asking for. You say you put a number in that was wrong. What was that number?

 

[Sheilala168]

your suppose to subtract the two answers you got.
0.083-0.0812 to get the difference in diameters.
You might want to check you calculations too.