I have a big question(Dynamics-Parallel Velocities)

[Queren Suriano]

In this problem why it is not considered that the bar is in translation (angular velocity = 0) if at the time when the angle is 0 °, the velocities at each point of the rod are parallel??

 

[jack action]

They might be parallel, but they don't necessarily have the same magnitude.

 

[Queren Suriano]

Your comment made me realize that to affirm that the angular velocity is zero, must be checked with a relative velocity analysis, in this case Vab = Va + V b / a; (Vab) x (i) + (Vab) y (j) = Va (i) + [w (k) x (L / 2 (j))] where simplification is that (Vab) y = 0; (Vab) x = Va + (wL / 2); where it exists angular velocity.

Thank You!