Speed of Circular Motion

vCalc Reviewed
Equation / Last modified by AndrewBudd on 2018/10/12 16:51
vCalc.Speed of Circular Motion

The Speed of Circular Motion calculator computes the speed (s) of a particle or point in uniform circular motion based on the radius (r) of the orbit and the period of rotation, T.
INSTRUCTIONS: Choose your preferred units (e.g. nano-meters or milliseconds) and enter the following:

  • r This is the radius defining the orbit of circular motion.
  • T This the orbital period of rotation.

The calculator computes the Speed of Circular Motion (v) in meters per second.  However this can be automatically converted to numerous other velocity units via the pull-down menu.

Exercise: Choose Years as the units for period, and Astronomical Units as the unit for radius.  Then enter 1 as the value for both.  The resulting velocity is the speed that the Earth travels about the Sun.  Then use the pull-down menu to see the result in miles per hour (mph).

The Math

The angular frequency is the number of increments of `2*pi` radians (`2*pi` radians is one complete rotation) divided by the period of the rotation, outputting simply rotations per unit time.

The distance around the circular path is ` d = 2*pi*r` (`2*pi` radians is one complete rotation) and then  `v = d / T` is the velocity.

So, `v = (2*pi*r) / T`  

Other Circular Motion Functions

  • Centripetal Acceleration as a function of tangential velocity and radius, CLICK HERE.
  • Angular Frequency as a function of orbital period, CLICK HERE.
  • Radial Acceleration as a function of orbital period and radius, CLICK HERE.
  • Acceleration in non-uniform Circular Motion, CLICK HERE.


  1. ^ Young, Hugh and Freeman, Roger.  University Physics With Modern Physics.  Addison-Wesley, 2008. 12th Edition, (ISBN-13: 978-0321500625 ISBN-10: 0321500628 ) Pg 89, eq 3.29