Pneumatic circuit following devices operate using compressed gases, but are not normally thought of as being pneumatic circuits: Pneumatic circuit A pneumatic circuit is an interconnected set of components that convert compressed gas (usually air) into mechanical work. In the normal sense of the term, the circuit must include a compressor or compressor-fed tank. The circuit comprises the following components: In general, based on the application, a pneumatic cylinder is usually a single acting cylinder, where there is a single port in the cylinder and where cylinder extension is done by compressed air and retraction by means of open coiled spring. In
Potential energy distance at which "U" becomes zero: formula_34 and formula_35. The choice of formula_36 at infinity may seem peculiar, and the consequence that gravitational energy is always negative may seem counterintuitive, but this choice allows gravitational potential energy values to be finite, albeit negative. The singularity at formula_34 in the formula for gravitational potential energy means that the only other apparently reasonable alternative choice of convention, with formula_36 for formula_34, would result in potential energy being positive, but infinitely large for all nonzero values of "r", and would make calculations involving sums or differences of potential energies beyond what is possible