We show how a two-body potential may be uniquely determined from n-bod
y spectra in cases where the hypercentral approximation is valid. We i
llustrate this by considering a harmonic-oscillator potential which ha
s been altered by changing the energy or normalization constant of the
ground state of the n-body system and finding how this modifies the t
wo-body potential. It is shown that, with an increasing number of part
icles, the spectrum must be known more precisely to obtain the two-bod
y potential to the same degree of accuracy.