< Mentor Note -- thread moved to HH from the technical engineering forums, so no HH Template is shown > A rod rolls without creep. And the disk rolls without creep on Q. The rod can just moves on y. Which is the relation among Va and Vohm? Va= velocity in A My resolution: in Q we know that velocity is zero.Q is also the instant rotation center ( disk).so the P point ( disk) is the fastest. How to bound speed in ##\Omega## and Va? I mean, just seeing the picture, without using the fondant formula of rigid cinematic. I could think it's like the half of Va. Ps.it's my first article and my english isn't so good, I hope you'll understand anyway.