Problem $10$: The angular velocity of link AB is ${}_{AB}=5ra\frac{d}{s}.$ At the instant $=45$ and $=30$ :

a$)$ Determine the velocity of block $C$ and the angular velocity of link $BC$

b$)$ Determine acceleration of block $C$ if the angular acceleration of rod $AB{}_{AB}=1ra\frac{d}{s^2}CW($clockwise direction$)$