(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

A)Find the moment of inertia tensor for a system of 4 particles of mass 1kg at A=(1,1,0), B=(1,-1,0) C=(-1,1,0) D=(-1,-1,0) in Cartesian coordinates.

B)Rotate the coordinates 30 degrees around the z axis and find the tensor in the new coordinates.

2. Relevant equations

Ixx=[itex]\sum[/itex]y^2+z^2

Iyy=[itex]\sum[/itex]x^2+z^2

Izz=[itex]\sum[/itex]y^2+x^2

Ixy=[itex]\sum[/itex]xy

Iyx=[itex]\sum[/itex]yx

Izx=[itex]\sum[/itex]zx

Izy=[itex]\sum[/itex]zy

I'=RIR*

3. The attempt at a solution

I get Ixx=4, Iyy=4, and Izz=8. Anything multiplying z is 0 and all the xy components cancel out. So a diagonal matrix.

For B I just apply the z rotation matrix with 30,RIR*, but when I do this I get the same thing. This can't be right so I either calculated my starting matrix wrong or am rotating incorrectly.

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# Homework Help: Point Mass Inertia Tensor

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