Editing Right-hand rule (section)

==Rotations==
===A rotating body===
[[File:Right-hand grip rule.svg|thumb|right|Conventional direction of the axis of a rotating body]]

In mathematics, a rotating body is commonly represented by a [[pseudovector]] along the axis of [[rotation around a fixed axis|rotation]]. The length of the vector gives the [[Angular velocity|speed of rotation]] and the direction of the axis gives the direction of rotation according to the right-hand rule: right fingers curled in the direction of rotation and the right thumb pointing in the positive direction of the axis. This allows some simple calculations using the vector cross-product. No part of the body is moving in the direction of the axis arrow. If the thumb is pointing north, [[Earth's rotation|Earth rotates]] according to the right-hand rule ([[retrograde and prograde motion|prograde motion]]). This causes the Sun, Moon, and stars to [[diurnal motion|appear to revolve]] westward according to the left-hand rule.

===Helixes and screws===
[[Image:Screw thread handedness.png|thumb|right|Left- and right-handed screws]] 
A [[helix]] is a curved line formed by a point rotating around a center while the center moves up or down the ''z''-axis. Helices are either right or left handed with curled fingers giving the direction of rotation and thumb giving the direction of advance along the ''z''-axis.

The threads of a [[screw]] are helical and therefore screws can be right- or left-handed. To properly fasten or unfasten a screw, one applies the above rules: if a screw is right-handed, pointing one's right thumb in the direction of the hole and turning in the direction of the right hand's curled fingers (i.e. clockwise) will fasten the screw, while pointing away from the hole and turning in the new direction (i.e. counterclockwise) will unfasten the screw.