please calculate beta when the friction coefficient is 0.4(use work and energy method)

oroblem 03/73 A small vehicle enters the top A of the circular path with a horizontal velocity v0 and gathers speed as it moves down the path. Determine an expression for the angle which locates the point where the vehicle leaves the path and becomes a projectile. Evaluate your expression for v0=0. Neglect friction. Fr=mar,mgcos+N=m(rr2)=mRv2F=ma,mgsin=ma,a=(r+2r)=gsinvdv=ads,v0vvdv=0gsin(Rd)v2=v02+2gR(1cos)N=mgcosmRv022mg(1cos)=mg(3cos2gRv02)WhenN=0,so=cos1(32+3gRv02)Forv0=0,=cos1(32)=48.2