Which statement best describes semi-conductors? Lack free electrons that can move to other atoms Electrons within their atoms are strongly held by the nuclei Most electrons within their atoms are paired Electricity can flow through it under special conditions

Two steel balls, each of mass m, are welded to a light rod of length l and negligible mass and are initially at rest on a smooth horizontal surface. a horizontal force of magnitude f is suddenly applied to the rod as shown. determine (a) the instantaneous acceleration a of the mass center g and (b) the corresponding rate at which the angular velocity of the assembly about g is changing with time.