Task: Text Categorization
Input (English): The tensor analog of this quantity can be diagonalized by defining a coordinate system along the principal axes, and its middle eigenvalue corresponds to unstable motion according to Euler's Equations of Motion. The deflection of a cantilevered beam is inversely proportional to Young's modulus and this quantity. It is given by "cross-sectional area times the square of the radius of gyration", and it can be found by the parallel axis theorem. For a sphere it is equal to "two-fifths m r squared", while it has half the value for a disc that it has for a ring. For 10 points, name this quantity symbolized "I", the rotational analog of mass.
Output (English): Science