The amount of meat in prehistoric diets can be determined by measuring the ratio

Question

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 15N, 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) atoms of speed 8.50km/s and want to bend them within a uniform magnetic field in a semicircle of diameter 25.0cm for the 12C. The measured masses of these isotopes are 2.32

Explanation / Answer

The radius R is determined by the formula

R = mv/qB,

q=same for all, +1, because they all lack 1 electron.

B = magnetic field is the same for all,

v = 8.5 km/s is described to be the same for all

Thus,

R(C-12)=m(C-12)v/qB --------(1)

R(N-14)=m(N-14)v/qB--------(2)

R(N-15)=m(N-15)v/qB---------(3)

Dividing (1) by (2),we have

R(C-12)/R(N-14)=m(C-12)/m(N-14)

R(N-14)=R(C-12)*m(N-14)/m(C-12)

=25*2.32

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