Engine (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. A pneumatic motor is a machine that converts potential energy in the form of compressed air into mechanical work. Pneumatic motors generally convert the compressed air to mechanical work though either linear or rotary motion. Linear motion can come from either a diaphragm or piston actuator, while rotary motion is supplied by either a vane type air motor or piston air motor. Pneumatic motors have found widespread success in the hand-held
Potential energy the gravitational potential, often denoted by formula_47 or formula_48, corresponding to the energy per unit mass as a function of position. The gravitational potential energy of two particles of mass "M" and "m" separated by a distance "r" is The gravitational potential (specific energy) of the two bodies is where formula_51 is the reduced mass. The work done against gravity by moving an infinitesimal mass from point A with formula_52 to point B with formula_53 is formula_54 and the work done going back the other way is formula_55 so that the total work done in moving from A to B