Task: Text Categorization
Input (English): The spherical helix is the tangent indicatrix of a curve of constant this. A relativistic form of it occurs for bound electrons due to their being in non-inertial frames and is named for Thomas. Vector quantities generally undergo this phenomenon when orthogonal to their time derivatives. A second-order type of this motion is called nutation. Analysis of the best-known type of it requires the understanding that the torque due to gravity is the time derivative of the angular velocity. FTP, name this physical phenomenon, a periodic change axial direction of a rotating object, exhibited by gyroscopes and spinning tops.
Output (English): Science