What is the Instant Centre of Rotation for a Rotating Bar?

[Hidd]

Homework Statement

Homework Equations

orthogonality condition: that means that the point of ICR is orthogonal to the velocity Vb and Va

The Attempt at a Solution

the solution that i found with the problem is:
The ICR of the bar is at infinity. the motion of the bar is translational.

I think that the answer is wrong because the point A is rotating, thus the the velocity of vb is not parallel to Va.

 

[BvU]

I agree with you. Only if a = 0 are the velocities parallel -- and then the bar does indeed not rotate