__Return to current section__**: ****Circular Motion Model****.**

In the diagram below, you can drag the black dot pointed to by initial radial vector **r**_{0} and the blue dot pointed to by

vector **r**(*t*). The standard angle values (zero at the rightward horizontal, increasing in the CCW direction) are shown at

the upper left of the diagram, updating as the dots are moved. In the general case, *θ*(*t*) can be any function of time.

Its time derivative is designated *ω*(*t*). For **Uniform Circular Motion** (UCM), *ω *is a constant. Multiplying any vector

in the plane on the left by the unit CW bivector **i** rotates the vector a quarter turn CCW. We can see the direction of

the velocity vector {**v**(*t*) = *ω*(*t*) **i r**(*t*)} in the diagram riding along with **r**(*t*). A green unit circle is also shown, as well

as the purple arclength *s* = *r**θ* created by the blue dot's motion.