V2/R - Is There An Easy Way Using Plar Coords

[Peter Pedant]

Hi babies
A level 1965 - the maff master showed us a really easy derivation of a= v2/ r or a rw2
using polar coords, differentiation (twice) and the grouping terms

and I cant remember it. I cant remember the start
was it x = r costheta and y r sintheta - and off you go differentiating, x-dot etc
or
was it r = ....

help please - doing a bit about tropical storms - Coriolis effect
an imaginary force - but the storms really do rotate so it isnt that imaginary is it?

thx - I know there are few mathematicians lurking out there

[Peter Pedant]

Polar - polar - I can spell Polar for chrissakes