A researcher uses laser cooling (see Problem 47) to build an atomic trap that contains rubidium atoms of mass 1.42 × 10-25 kg. If the atoms are separated by 75 nm on average, what speed should they have so that their de Broglie wavelengths are equal to their average separation? (In general, overlapping de Broglie waves lead to quantum behavior. This is the basic technique used to produce a Bose-Einstein condensate, which is a quantum state of matter.)