Given: thin smooth wire is situated in vertical plane and has a shape of circle arc of radius R=2,3m. A small ball of mass m=441g is placed on this wire moving along it from point A with initial speed VA=8,6m/s. Points A and D are specified by angles α=66 degrees and β=18 degrees; point B is the lowest point of the wire.
Find: ball speed at point D — VD=?