A spring attached at $A$ is unstretched $($no force in spring$)$ when slider $P$ is at the top of the semicircular slot. Determine the force in the spring when slider P is at position $=90.$ Then give the spring force at P $($directed towards A $)$ in rectangular components using unit vectors. Use $r=500mm$ and spring constant $k=1\mathrm{.}5k\frac{N}{m}.$