Why was the geocentric model the leading theory for such a long time even though the heliocentric model more simply explain the observed motions and brightness of the planets

Although the heliocentric theory is simpler and corresponds to the observed movements, both Galilean and Kepler presented sufficient evidence to contradict this model. It is obvious that it cost a little to be accepted by the scientific community and certainly religion generated many difficulties, however the sociopolitical context of Europe and America would make this theory more and more accepted by the population

mass and volume are the answers you are looking for

e/c, where e is its total energy