Back in engineering school years ago, we learned of static and dynamic balance. We learned that two dimensional objects (very small depth compared to length or diameter) could be static balanced. Three dimensional objects (large depth compared to length or diameter; IE. crankshaft) require dynamic balance. Now I read here and other places about props that have blades and hubs balanced. I don't understand what they're talking about.

Is there someone here who can set me straigtht with a good, technical explanation of balance. Thanks