Editing Trajectory (section)

{{short description|Path of a moving object}}
{{other uses|Trajectory (disambiguation)}}
{{redirect|Flightpath}}
{{citations needed|date=July 2022}}
[[File:RiflemansRule.svg|thumb|350px|Illustration showing the directional trajectory of a bullet fired at an uphill target]]

A '''trajectory''' or '''flight path''' is the path that an [[physical body|object]] with [[mass]] in [[Motion (physics)|motion]] follows through [[space]] as a function of time. In [[classical mechanics]], a trajectory is defined by [[Hamiltonian mechanics]] via [[canonical coordinates]]; hence, a complete trajectory is defined by position and [[momentum]], simultaneously.

The mass might be a [[projectile]] or a [[satellite]].<ref>{{cite book |title=The Principles of Physics |first=Rohit |last=Metha |chapter=11 |page=378}}</ref> For example, it can be an [[orbit]] — the path of a [[planet]], [[asteroid]], or [[comet]] as it travels around a [[primary (astronomy)|central mass]].

In [[control theory]], a trajectory is a time-ordered set of [[state (controls)|state]]s of a [[dynamical system]] (see e.g. [[Poincaré map]]). In [[discrete mathematics]], a trajectory is a sequence <math>(f^k(x))_{k \in \mathbb{N}}</math> of values calculated by the iterated application of a mapping <math>f</math> to an element <math>x</math> of its source.