Two identical hollow cylindrical neodymium iron boron (NdFeB) magnets are placed on a nonmagnetic post so that one is suspended directly above the other. The magnets are magnetized along the cylinder axes, and friction is negligible. The NdFeB material has a permanent magnetization of 8.90E+5 A/m, and a density of 7650 kg/m3. Each magnet has length 6.30 mm, outer diameter 6.35 mm, and inner diameter 2.70 mm.
Assuming the magnets behave as ideal dipoles, what is the distance between their centers?