please help, I would really appreciate it

Problem $3$:

A double link arm rotates within the vertical plane, with point $O$ inertially fixed and point $Q$ as elbow. The primary arm measures at angle $$ relative to right horizontal, and the secondary arm measures at $$ also relative to right horizontal but in the clock$-$wise direction. $l_1=1m,l_1=2m.$ Both ground surfaces are horizontal $($along hat$(e{)}_1).$

You are free to define additional reference frames or quantities that are helpful, and find:

$($a$)$ Kinematic expression of $P\text{'}$s inertial velocity.

$($b$)$ Use your velocity expression to deduct the ratio of ${}^{}$ and ${}^{}$ when $=30$ and also $=30,$ so that $P$ stays on the horizontal surface. Hint: $P\text{'}$s velocity will be zero in the hat$(e{)}_2$ component.