What is the Velocity at the Bottom of a Roller Coaster with Given Parameters?

[nohkie]

Homework Statement

A roller coaster with radius of 19.6 and at the top of the roller coaster the veloctiy is 14 m/s and the apparent weight is 0. Calculate the veloctiy at the bottom of the roller coast?

Homework Equations

The Attempt at a Solution

I can see that Mv^2/r=mg at the top but i don't get how to solve for the veloctiy at the bottom of the equation of mv^2/r = Fn-mg. Am I looking in the right direction? I've done the force body diagram but the only way i can see to get out the velocity is with mass, am I missing an equation?

 

[haruspex]

Think about potential and kinetic energy.