Editing Angular acceleration (section)

{{Short description|Physical quantity}}
{{Infobox physical quantity
| name = Angular acceleration
| unit = rad/s{{sup|2}}
| otherunits =
| symbols = '''α'''
| baseunits = s<sup>−2</sup>
| dimension = wikidata
| transformsas = pseudovector
}}
{{Infobox unit
| name     = Radians per second squared
| standard = [[SI derived unit]]
| quantity = Angular acceleration
| symbol   = rad/s{{sup|2}}
}}
{{Classical mechanics|expanded=rotational}}

In [[physics]], '''angular acceleration''' (symbol '''α''', [[alpha]]) is the [[time rate of change]] of [[angular velocity]]. Following the two types of angular velocity, ''spin angular velocity'' and ''orbital angular velocity'', the respective types of angular acceleration are: '''spin angular acceleration''', involving a [[rigid body]] about an [[axis of rotation]] intersecting the body's [[centroid]]; and '''orbital angular acceleration''', involving a point particle and an external axis.

Angular acceleration has [[physical dimension]]s of angle per time squared, measured in [[SI unit]]s of '''radians per second squared''' ('''rad{{sdot}}s<sup>−2</sup>'''). In two dimensions, angular acceleration is a [[pseudoscalar]] whose sign is taken to be positive if the angular speed increases counterclockwise or decreases clockwise, and is taken to be negative if the angular speed increases clockwise or decreases counterclockwise. In three dimensions, angular acceleration is a [[pseudovector]].<ref name="ref1">{{cite web |title=Rotational Variables |url=https://phys.libretexts.org/Bookshelves/University_Physics/Book%3A_University_Physics_(OpenStax)/Map%3A_University_Physics_I_-_Mechanics%2C_Sound%2C_Oscillations%2C_and_Waves_(OpenStax)/10%3A_Fixed-Axis_Rotation__Introduction/10.02%3A_Rotational_Variables |website=LibreTexts |date=18 October 2016 |publisher=MindTouch |access-date=1 July 2020 |ref=1}}</ref>