In the four$-$bar linkage shown below, the control link $BC$ has a counter$-$clockwise constant angular velocity ${}_0=1ra\frac{d}{s}.$ Consider the mass center of each link be at its midpoint. At the instant when $OA$ is vertical upward,

$(1)$ calculate the mass center coordinate of each link, $(5\%)$

$(2)$ the angular velocity of all the links $(5\%),$ and

$(3)$ the angular acceleration of all the links $(5\%),$

$(4)$ the velocity and acceleration of at the midpoint of $AB(10\%),$ and

$(5)$ the instantaneous center of rotation of $AB.(5\%)$