Okay, I think I'm getting somewhere. Would it be right to say the Fc is equal to the x-factor of the weight of the mass on the string? I could say this therefore:
Fc = mgsin(theta)
and then
sin(theta) = mv^2/mgsin(theta)L
which would cancel mass, giving me:
sin(theta) =...
"A mass of 3.900 kg is suspended from a 1.450 m long string. It revolves in a horizontal circle.
The tangential speed of the mass is 3.247 m/s. Calculate the angle between the string and the vertical (in degrees)."
Here is a diagram, labelling angle theta I'm supposed to solve for...