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Fri 11 Jul, 2014 01:47 pm
A cylindrical iron bar, 6 feet in length and 2 inches in diameter, is formed into a square bar with a cross section of 2. 25 square inches.
Find length of the new bar.
What is known:
An iron bar is cylindrical, 6 feet long, 2 inches in diameter.
The cylinder is formed into a square bar with a cross section of 2.25 inches.
Want to know:
Length of the new bar.
Volume of cylinder- pi * r^2 * h ( unknown if needed).
A square has equal sides.
Not sure how to proceed. Thanks.
@Randy Dandy,
As you didn't say it was cut, it still is 6 feet long..
(You must have missed something)
@Randy Dandy,
The volume before and after are the same. As you mentioned, the volume before can be computed from your formula. The volume after is just AxL where A is the area you are given (2.25 sq in). So:
pi * r^2 * h = A x L
and you know r = 1 inch, h = 6 ft, A = 2.25 in^2. Solve for L
@engineer,
I didn't think it was passed through a rolling mill..
pi * r^2 * h = A x L
3.14 * .0833 * .0833 * 6 = 2.25^2 x L
0.13082 = 2.25 ^ 2 x L
0.13082 = 5.0625 L
0.13082 = 5.0625L
______ _______
5.0625 5.0625
L = 0.02584
I think that is not correct.
@Randy Dandy,
You have two mistakes in your math. First, you converted radius to feet but left the area in the other side in inches. The second error is that you don't square the area on the right hand side, it is already an area value. This is what it should look like:
pi * r^2 * h = A x L
3.14 * 1^2 * 6 = 2.25 * L
@engineer,
pi * r^2 * h = A x L
3.14 * 1^2 * 6 = 2.25 * L
18.84 = 2.25L
18.84/2.25 = 2.25/2.25
8.3733 = L
I have a feeling I have omitted something.
@Randy Dandy,
If I understand the problem correctly, all you forgot was to put "feet" after the answer.
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