# Block sliding off a table

A small block slides on a horizontal friction-less surface $$AB$$ of a table with speed $$\frac { 1 }{ 2 } \sqrt { gR }$$. At some point $$B$$, the track becomes circular with radius $$R$$ (look at the diagram). The block leaves the table at a certain point $$C$$. Determine the angle $$\alpha$$.

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