Abstract: We investigate the variable mass problem in the undergraduate physics teaching and nuclear physics. The falling chain problems and relativistic mass are involved by considering the derivation of the elementary work. Moreover, we also discuss the properties of the equivalent quark mass in the nuclear physics teaching and compact star physics research. Our results indicate that considering the variable equivalent quark mass can significantly influence the equation of state of quark star matter and the maximum mass of quark stars.

Key words: nuclear matter, equivalent quark mass, relativistic mass