1. The problem statement, all variables and given/known data The velocity of end 'A' of rigid rod placed between two smooth vertical walls moves with velocity 'u' along vertical direction. Find out the velocity of end 'B' of that rod, rod always remains in contact with the vertical walls. 2. Relevant equations 3. The attempt at a solution I have no idea where to start from. Should i take the component of 'u' along the rod? But if so, then why should i do it?