Nuclear magnetic resonance (NMR) is a technique for analyzing chemical structures and also the basis of magnetic resonance imaging used for medical diagnosis. NMR relies on sensitive measurements of the energy needed to flip atomic nuclei by 180° in a given magnetic field. In an apparatus with a 9.4-T magnetic field, what energy is needed to flip a proton (m = 1.41x10^-26 Am²) from parallel to antiparallel to the field?