Hey guys. Heard about this forum from a friend and decided to join up. Just so you guys know, some of my questions are pretty random and weird , hope i don't annoy you fellas... Alright, first question i got. http://img170.imageshack.us/img170/5953/00000000zd3.png [Broken] say you have 2 arms connected to a shaft, the arms are hinged which allows them to move up and down . The arms weigh 2.5lbs each and are 10 inches long. How do you figure out at what rpm the shaft has to spin at in order for the arms to be perpendicular to the shaft?