The amount of meat in prehistoric diets can be determined by measuring the ratio of the isotopes nitrogen-15 to nitrogen-14 in bone from human remains. Carnivores concentrate 15N15N, so this ratio tells archaeologists how much meat was consumed by ancient people. Suppose you use a velocity selector to obtain singly ionized (missing one electron) nitrogen atoms of speed 8.50 km/skm/s and bend them along a semicircle within a uniform magnetic field. The 14N14N atoms travel along a semicircle with a diameter of 29.2 cmcm. The measured masses of these isotopes are