It can also be used to study motion in a central potential. If the central potential is of the form U ∝ ∝ r n , the virial theorem simplifies to ⟨ ⟨ T ⟩ ⟩ = n 2 ⟨ ⟨ U ⟩ ⟩ . In particular, for gravitational or electrostatic (Coulomb) attraction, ⟨ ⟨ T ⟩ ⟩ = − − 1 2 ⟨ ⟨ U ⟩ ⟩ .