expert help $($b$)$ The disc in Figure $3\mathrm{.}2$ has diameter $1$ m and is rolling on the level ground with angular

velocity $4ra\frac{d}{s}.$ Bar $AB$ has length $1$ m and is attached to the disc at $A,$ while $B$ slides

on the ground.

Determine the angular velocity of bar $AB$ and the velocity of point $B.$

$[9$ Marks$]$

Figure $3\mathrm{.}2$