Q.Define - gravitational potential.

Gravitational potential is defined the same way as electric potential, but for gravity: it is the work needed per unit mass to bring a test mass from far away (infinity) to the given point, and works out to V = -GM/r for a point mass (or spherical mass) M.

Definition: The gravitational potential (V) at a point in a gravitational field is the amount of work done in bringing a unit mass (1 kg) from infinity to that point, without giving it any acceleration (i.e., quasi-statically, against the gravitational pull).

For a point mass (or uniform sphere) of mass M, at a distance r from its centre:

V = -GM/r

where G is the universal gravitational constant.

Key points:

• V is a SCALAR quantity (unlike gravitational field, which is a vector).
• SI unit: J/kg (or equivalently, m²/s²). …