A point-like object that undergoes circular motion changes its angular position from initial Θ_{i} to final Θ_{f}, relative to a fixed axis, specified in a coordinate system with an origin that coincides the centre of the circular path of object. The change in its angular position is called angular displacement ΔΘ = Θ_{f} - Θ_{i}. Also, a rigid body that rotates about a specified rotation axis, changing its angular position from initial Θ_{i} to final Θ_{f}, undergoes an angular displacement ΔΘ.

The average angular velocity, ω_{av}, is the ratio of the angular displacement and the time interval Δ*t*=*t*_{f}-*t*_{i}, in which that displacement occurs.

ω– =

Θ_{f} - Θ_{i}
/
*t*_{f} - *t*_{i}

=
ΔΘ
/
Δ*t*

Θ_{f} and Θ_{i} are the initial and final angular position, respectively.

The instantaneous angular velocity *ω* is the limit of the average angular velocity, as Δ*t* is made to approach zero.

ω =

lim
Δ* t*→0

ΔΘ
/
Δ*t*

=
dΘ
/
d*t*

*ω*_{av} and ω are positive for the counterclockwise rotation (in direction of increasing Θ) and negative for the clockwise rotation (in direction of decreasing Θ).

SI unit for angular velocity is s^{-1}.The measure for the angle Θ is radian. The relationship between radians and degrees is:

2π rad = 360°

For example, the angular velocity of the minute hand of a clock is:

ω =
^{-1}

2πrad
/
360 s

= 1.74 msGeneralic, Eni. "Angular velocity." *Croatian-English Chemistry Dictionary & Glossary*. 20 Oct. 2018. KTF-Split. {Date of access}. <https://glossary.periodni.com>.

Glossary

Periodic Table

Copyright © 2018 by Eni Generalic. All rights reserved. | Disclaimer