**...**

Oooo thats an interesting way(easy too)

Mine was probably half right(and crap long way)

x = rcos@

y = rsin@

i d/dt ( ) both sides twice for x and y

x* = -rsin@ d@/dt = -r@*sin@

x** = -r[@**sin@ + @*cos@.d@/dt ]

= {-r@**sin@} - {r@**cos@ }

did the same for y and took the second { } bracket from the x** and y** and tried to add them like vectors to get r@** but was getting confused and it pointed north west ????? its not meant to

i didnt get why but then i just said this is acceleration and times it by the mass to get force..

Pretty crap explainer.

I got this method from arnold the day before and only skim read it , thats why i was confused in the exam. I DIDNT THINK IT'LL COME.