Given the task definition and input, reply with output. In this task you will be given a text passage from a trivia quiz. You should choose the category this question belongs to from these categories: History, Science, Social Science, Fine Arts, Literature. You can only choose one category, so if in doubt, please choose the closest match.

The tennis racket theorem describes an asymmetric instability that arises when this quantity's principal components are all distinct. The diagonalization of this quantity yields three values which define the axes of Poinsot's ellipsoid. Its scalar form can be calculated as the integral of r-squared dm, and it is unchanged when the object is stretched parallel to the (*) axis of rotation. Given its value at the center of mass, it can be calculated for the same object about a parallel axis. This quantity equals torque divided by angular acceleration, as well as angular momentum divided by angular velocity. For 10 points, name this quantity symbolized I, the rotational analog of mass.
Science