Height increase h = R*(1 - cosΘ) = 1.2*(1-cos3.5°) = .00224 m.
½Mbl*Vbl² = Mbl*g*h →
Vbl = √(2gh) = .2095 m/s
This is the initial velocity of the block. From momentum considerations,
Mbt*Vbt = Mbl*Vbl →
Vbt = (Mbl/Mbt)*Vbl = (5/.002)*.2095 = 523.8 m/s
this is what i think the answer is im not for sure though... hope it helps...