Constants at the surface of a certain planet, the gravitational acceleration g has a magnitude of 15.0 m/s.. a 31.0-kg brass ball is transported to this planet part a what is the mass of the brass ball on the earth and on the planet? express your answers using three significant figures separated by a comma. part b what is the weight of the brass ball on the earth and on the planet? express your answers using three significant figures separated by a comma.