$(15$ points$)$ The two blocks A and $B$ have mass $400$ grams and $500$ grams, respectively. The blocks are fixed to the horizontal rods, and their initial velocity along the circular path $2\frac{m}{s}.$ If a couple moment of $M=(0\mathrm{.}5t)Nm$ is applied about $CD$ of the frame, determine the speed of the blocks when $t=3$ seconds. The mass of the frame is negligible, and it is free to rotate about $CD.$ Neglect the size of the blocks.