Task: Text Categorization
Input (English): A system named for Rott features has two of these structures with horizontal SFP and BFPs at stable equilibria. In the phase-space representation for the system, the upper-half of the separatrix shows solutions for these systems starting at their inverted positions. Two coupled ones are commonly used to represent chaotic systems. When their displacements are assumed to be small, the sine theta term in the equation is approximated to theta. Another of these was used to demonstrate the rotation of the earth and was named for Foucault. For 10 points, identify these physical systems which can be used to model simple harmonic motions, and which swing back and forth in some clocks.
Output (English): Science