#5.4.4a
gravitational potential at a point as the work done in bringing unit mass from infinity to the point; gravitational potential is zero at infinity
#5.4.4b
gravitational potential \(V_g = -\dfrac{GM}{r} \) at a distance r from a point mass M; changes in gravitational potential
#5.4.4c
force–distance graph for a point or spherical mass; work done is area under graph
#5.4.4d
gravitational potential energy \(E = mV_g = -\dfrac{GMm}{r} \) at a distance r from a point mass M
#5.4.4e
escape velocity.