In which calculation would the use of the mass-energy equivalence principle be needed? A. energy obtained from the burning of fossil fuels B. energy given off by a current flowing through a wire C. energy created by the conversion of mass of a uranium sample D. mass of coal burned in order to provide the energy needed for a large city

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.