For 10 points, name these machines, exemplified by a wheel around which a rope moves.
Though not pendulums, a dynamical system of two of these machines, in which one mass is free to swing in a plane and a larger mass moves only up or down, exhibits chaotic or complex harmonic motion. In a system of two of these machines, for two masses x and y, the acceleration experienced by both masses is x minus y over x plus y, all times little-g. An Atwood machine has two ideal, frictionless examples of these machines, which are connected in a block and tackle. For 10 points, name these machines, exemplified by a wheel around which a rope moves.
Though not pendulums, a dynamical system of two of these machines, in which one mass is free to swing in a plane and a larger mass moves only up or down, exhibits chaotic or complex harmonic motion.
pulleys [accept Atwood's machines before mentioned]