We propose an epistemic measure of physics in terms of the ability to discriminate between the
purely mathematical, physical (i.e. dependent on empirical inputs) and nominal (i.e. empty of
mathematical or physical content) propositions appearing in a typical derivation in physics. The
measure can be relevant in understanding the maths–physics link hurdles among college students. To
illustrate the idea, we construct a tool for a familiar derivation (involving specific heats of an
ideal gas), and use it for a sample of students from three different institutes. The reliability of
the tool is examined. The results indicate, as intuitively expected, that epistemic clarity
correlates with content clarity. Data yield several significant trends on the extent and kinds of
epistemic pitfalls prevalent among physics undergraduates.