$(5)$

A ball $p$ weighs $1kg.$ It is attached to an elastic cord with Spring constant $k=20\frac{N}{m}.$ The cord has an unstreched length $0\mathrm{.}20m.$ The ball is moved along path $r=0\mathrm{.}5sin$ by a slotted arm.

Find the force the arm applies to the ball when $=65,{}^{}=1ra\frac{d}{s},{}^{}=2ra\frac{d}{s}$

Assume the circle is horizontal. $($i$.$e$.$ ignore gravity$)$