Two collars are pin$-$connected and are allowed to move along the straight rod and the

curved guide, respectively. The shape of the guide is described by $r=100(2-cos)mm.$

If the rod rotates at a constant angular velocity, $5$ rad$/$s$,$ in the direction shown, find $($a$)$ the

speed and $($b$)$ the magnitude of the acceleration of the collar $($that is$,$ point B$)$ at the instant

$=120$