Formula Circular Motion Centripetal acceleration Radius Frequency
$$a_{ \text z } ~=~ 4\pi^2 \, f^2 \, r$$ $$a_{ \text z } ~=~ 4\pi^2 \, f^2 \, r$$ $$r ~=~ \frac{a_{ \text z }}{4\pi^2 \, f^2}$$ $$f ~=~ \frac{1}{2\pi} \sqrt{ \frac{ a_{ \text z } }{ r } }$$
Centripetal acceleration
$$ a_{\text z} $$ Unit $$ \frac{\mathrm{m}}{\mathrm{s}^2} $$ Acceleration, which a body (e.g. a planet, a particle) experiences, which moves on a circular path. The centripetal acceleration points like the centripetal force to the circle center (in radial direction).
Radius
$$ r $$ Unit $$ \mathrm{m} $$ Radius of the circular path. This is the distance from the center of the circle to the rotating body.
Frequency
$$ f $$ Unit $$ \mathrm{Hz} = \frac{ 1 }{ \mathrm{s} } $$ The frequency indicates how many revolutions per second the body makes.