1. Jan 14, 2005

theoriginalh

Hi. I'm having trouble knowing where to start on a problem. Basically, I have to find the radius of gyration of this diamond shape, about an axis through its centre and perpendicular to the plane. All sides are 0.5m in length and from tip to tip horizontally it measures 0.8m. I'm not quite sure how to go about this. Any help would be appreciated.

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2. Jan 14, 2005

da_willem

You could calculate the moment of inertia from it's definition: $$I=\int r^2 dm$$ with $$r^2=x^2+y^2$$ and $$dm=\rho dxdy$$. Then you will have to use functions describing the shape in your integral limits. Or you can use the perpendicular axis theorem (http://hyperphysics.phy-astr.gsu.edu/hbase/perpx.html)