Q.Define gravitational potential.

Definition. The gravitational potential $V(r)$ at a distance $r$ from a source mass $m$ is the potential energy per unit mass at that point:

a scalar quantity (unlike the field $\vec{E}$), with SI unit joule per kilogram ($\text{J kg}^{-1}$).

Why a scalar version is useful. Gravitational field and force are vectors, requiring components and directions to combine correctly. Potential, being a scalar, adds up from multiple sources by simple algebra -- $V_{total}=V_1+V_2+\cdots$ -- which makes multi-mass problems dramatically simpler than working with vector fields directly. …