Past exam of the mathematics course of the University of Cambridge / 2014 / iii / Paper 50 / 2 / a

In geometrized units, a mass is converted to a length by multiplying its SI value by $G/c^2$, or to a time by multiplying by $G/c^3$. Using the supplied constants, the solar mass becomesThus the characteristic scales are kilometres and a few microseconds. With potential zero at infinity, the Newtonian gravitational potential at the surface, in units of $c^2$, isIts very small magnitude is the relevant weak-field measure. In SI potential units the same number corresponds to about $-1.91\times 10^{11}{\mathrm{m}}^2{\mathrm{s}}^{-2}$.