$1.$ If crank AB has a constant angular velocity of $160$ rpm counterclockwise, determine the angular velocity of rod BD and the velocity of collar D when:

a$)$ $=0$

b$)$ $=90$

$2.$ The crank arm AB has a constant angular velocity of $160$rpm counterclockwise. At the instant when $=0$:

c$)$ Determine the acceleration of the collar D

d$)$ Determine the acceleration of the midpoint G of the rod BD