A uniform rod rests on supports at its ends. The right support is quickly removed. The atom on the right end will accelerate faster than ##g## at ##1.5g##. How is this possible forces-wise? The only forces acting on the atom is its own weight and the interatomic forces of attraction, which acts horizontally (left) at the instant the right support is removed. So the net force on the atom doesn't seem to be able to make it accelerate faster than g.