The observation that these devices are not isochronous inspired Christiaan Huygens (“HOW-ginz”) to solve the tautochrone (10[1]-5[1])problem. (10[1]-5[1])The period of these devices (10[3]-5[1])depends (10[2])on their (10[2])initial displacement (10[6])and is proportional (10[5])to (-5[1])an elliptic (10[2]-5[3])integral (10[4])of the (10[2])first (10[1])kind. (10[8])A coupled pair of these (10[3])devices (10[4]-5[1])is a (10[1])classic (10[4])example (10[6])of (10[1])a (10[1])chaotic (10[6])system. (10[26]-5[1])When (10[1])these devices’ (10[3])equation of motion is linearized (-5[1])with the small angle approximation, (10[4])they can be (10[1])approximated as harmonic oscillators whose frequency is the square root of little g over L. (10[1])The Earth’s rotation causes the precession of a type of these devices (10[1])named for Léon Foucault (10[2])(“foo-KOH”). For 10 points, what devices consist of a mass (10[1])at the end of a rod? ■END■ (10[6])