Editing Angular displacement (section)

==Context==
[[Image:angulardisplacement1.jpg|class=skin-invert-image|upright=1.3|left|thumb|Rotation of a rigid body ''P'' about a fixed axis ''O''.]]
When a body rotates about its axis, the motion cannot simply be analyzed as a particle, as in [[circular motion]] it undergoes a changing velocity and acceleration at any time.  When dealing with the rotation of a body, it becomes simpler to consider the body itself rigid.  A body is generally considered rigid when the separations between all the particles remains constant throughout the body's motion, so for example parts of its mass are not flying off.  In a realistic sense, all things can be deformable, however this impact is minimal and negligible.