2) A cam is an approximately circular disk attached off center along a shaft. As the shaft rotates about its axis, the disk can be used to push something once every rotation. In internalcombustion engines, for example, this mechanism opens and closes intake and exhaust valves for the combustion chamber in synchronization with the piston's oscillations. One such shaft has radius 2cm and mass 3kg with an attached disk of radius 4cm and mass 0.3kg. The whole unit (\"camshaft\") is rotating at 300rpm