Conservation of energy with springs and rotational motion

[theBEAST]

Homework Statement

Homework Equations

T1 + V1 = T2 + V2

T = kinetic energy
V = potential energy

The Attempt at a Solution

I am only confused about how to get T2. Here is how the answer key gets T2:

I don't get why Va = Vb = 0. The wheels have some velocity so it doesn't make sense how they are zero. I realize that they won't rotate because there is no friction but I still think there is a velocity.

I also don't get why they can assume that the rods are pinned. How are they pinned when the spring stretches from √2 to 2m in length (this is from the solution as well)?

 

[lewando]

V_a=V_b=0 only when θ = 0. At this angle, AC and CB are horizontal and the maximum separation between A and B has been achieved.

''pinned" is not an assumption, it is expressly given--"All pin joints move without friction". Not sure what the answer key means by like "pinned case".