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Inertia, symmetry?

  • #1
rock.freak667
Homework Helper
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Homework Statement


I have to find the area moment of inertia about an axis 33 to the x-axis
http://img227.imageshack.us/img227/2392/shape.jpg [Broken]

Homework Equations


[tex]I_\phi=\frac{1}{2}(I_{xx}+I_{yy})+\frac{1}{2}(I{xx}-I_{yy})cos2\phi - I_{xy}sin2\phi[/tex]


The Attempt at a Solution



I found Ixx, but since it is symmetrical, Ixx=Iyy, and since it is symmetrical about the x and y axes, Ixy=0

So the I about any axis is just the 1/2(Ixx+Iyy) = Ixx.

Is my thinking correct, or am I mistaking it?
 
Last edited by a moderator:

Answers and Replies

  • #2
674
2
Looks ok to me.
 

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