PRINCIPAL AXES EXAMPLES

PRINCIPAL AXES EXAMPLES

EXAMPLE I
State the principal axes for the two-dimensional body shown in Figure 1↓.
figure images/circle.png
Figure 1 Two-dimensional circular body

ANSWER: Because of the symmetry through the point C, the products of inertia vanish for any line that goes through C. Therefore, any line drawn through C will be a principal axis.

EXAMPLE II
State the principal axes for a sphere.
ANSWER: Again, because of symmetry, a sphere will have all 3 axes drawn in any direction through C as a principal axis.