The force of gravity accelerates the mass 'm'. There is a critical height where mass 'm' flies off. How...

Question

The force of gravity accelerates the mass 'm'. There is a critical height where mass 'm' flies off. How fast is it going, using only R, h and gravity = 9.81 m/s^2? Here is the picture you will need to use for the problem: http://session.masteringphysics.com/problemAsset/1011090/26/MWE_we_9.jpg

Answer 1

Using radial force (Fr):
Fr = m*v²/R
for this problem:
Fr = m*v²/R = mgcos(angle)
cos(angle) = h/R
substituting and rearranging we get:
v²=gh
this is the velocity at a given height but without height I'm stuck.