After spending yesterday evening trying i couldn't do it, today, 10 mins after posting it, i got it..
For all of you who were going to try, thanks..
I've been trying to unravel this equation, but i have not been successful.. I could use some help..
The equation is the application of the conservation of energy law..
(m/2) [(Rx' + Rx'cos(x))^2 + (-Rx'sin(x))] + mg(R+ Rcos(x)) = (m/2)(v^2) + mg2R
I guess i should really learn how to use Latex. Anyway, the x' represents the derivative of x, m the mass, g the gravity force.
I know it unravels to (x')^2 = (4gR(sin(x/2))^2 + v^2) / (4(R^2)(cos(x/2))^2), but i can't get there..