One end of light string ‘L’ is tied to a ball and the other end is connected to a fixed point O. The ball is released from rest with string horizontal and just taut. The ball then moves in a vertical circular path as shown in figure; let the velocity of ball at B and C be  ${\overrightarrow{V}}_B$ and  ${\overrightarrow{V}}_C$ respectively. If  $\left|{\overrightarrow{V}}_C\right|=2\left|{\overrightarrow{V}}_B\right|$ then the value of $8\sin \theta$  is