Question about Applying V^2/r with two different velocities

[MaZnFLiP]

[SOLVED] Question about Applying V^2/r with two different velocities

Homework Statement

I have a problem where I am using the equation V^2/r = -1g to a problem with centripetal force. Basically the question is designing my own situation where i need to have a -1g acceleration on a turn and i decided on the picture below. It is a vertical picture.

Homework Equations

-1g = v^2/r

The Attempt at a Solution

I tried figuring out exactly how to get the velocity but I just don't seem to see which velocity to use.

 

[member 553083]

I know that the equation is V^2/r = -1g. I think the velocity I need to use is the final velocity, which is the velocity at the end of the arc, right? So in this case it would be the velocity of the car at the bottom after it has gone around the arc. So if I use the final velocity, the equation will be: Final Velocity^2/Radius = -1g Is this correct?