Circular motion and g force

[erucibon]

A trolley goes down a slope and then into a vertical circle, and there must be less than 5g at the top and bottom of the loop. Friction is ignored.

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

[jamonwindeyer]

A trolley goes down a slope and then into a vertical circle, and there must be less than 5g at the top and bottom of the loop. Friction is ignored.

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

Hey there erucibon! It's hard to know exactly where there could be holes in your method without seeing the question itself. Any chance you could share it so we can check your assumptions? Right now I don't know what you were trying to find, which parts of your answer(s) were off, or what the values in the question were