I my attempt, I set the drop height to 20m and using conservation of energy, i calculated the speed at the bottom. Calculating centripetal acceleration, if the radius of the circle is less than 10m then the g force is greater than 5, if equal to 10m the velocity at the top is 0 and there is 0 acceleration, and if radius is more than 10m then the velocity squared at the top is negative. When calculating the velocity at the top of the circle, i used conservation of energy.

Could someone please point out where I went wrong or if this approach is completely wrong? Thanks