When a particle has location [math]P(r,\theta)[/math] described with polar coordinates, we can express its position, velocity, and acceleration in terms of the moving unit vectors[br] [math]\mathbf{\mathbf{u}}_r=(\cos\theta)\mathbf{i}+(\sin\theta)\mathbf{j}[/math] and [math]\mathbf{\mathbf{u}}_{\theta}=-(\sin\theta)\mathbf{i}+(\cos\theta)\mathbf{j}[/math][br]

[i]This applet was developed for use with [url=https://www.pearson.com/en-us/subject-catalog/p/interactive-calculus-early-transcendentals-single-variable/P200000009666]Interactive Calculus[/url], published by Pearson.[/i][br]