What if your physics problem involves the same physical quantity twice, like speeds and masses of two bodies? Then single letter variable names are no longer un

What if your physics problem involves the same physical quantity twice, like speeds and masses of two bodies? Then single letter variable names are no longer unique nor meaningful. f(v_1, m_1, v_2, m_2) For the derivatives I would prefer writing d_v_2 f instead of d_3 f when counting arguments from 1