section_path: Types/Physically powered motor
section_name: Physically powered motor
paragraph_text: Physically powered motor
  
  Some motors are powered by potential or kinetic energy, for example some funiculars, gravity plane and ropeway conveyors have used the energy from moving water or rocks, and some clocks have a weight that falls under gravity. Other forms of potential energy include compressed gases (such as pneumatic motors), springs (clockwork motors) and elastic bands.
  
  Historic military siege engines included large catapults, trebuchets, and (to some extent) battering rams were powered by potential energy.