Part $1$: The crank arm B$1$ rotates clockwise about the pinned end O with an angular speed of $10$ rad$/$s$.$ If the angular speed of B$1$ is decreasing at a rate of $5$ rad$/$s$2,$ find $($a$)$ the velocity and $($b$)$ the acceleration of the piston pin at B at the given instant.

Part $2$: Solve part $($a$)$ of the problem again using the instant center. $($Note: There is no need to solve for the acceleration. The instant center method does not help in the acceleration analysis.$)$