1. The problem statement, all variables and given/known data Determine the angular velocity of the gear at the instant shown. Set v = 9ft/s and vc = 6ft/s. Assume counterclockwise is positive. 2. Relevant equations v = w x rIC 3. The attempt at a solution I tried solving this many times using va = v0 + (ω x ra0 ) and vb=v0 + (ω x rb0 ) but kept getting the wrong answer. Then I ended up solving for the instantaneous center using similar triangles and used v = ωxrIC. How do I know when to use an instantaneous center in my problem solving?