From algebraic substitution of these into the above relations, one derives Newton's law of universal gravitation : F = m 2 π π c k B T ℏ ℏ = m 4 π π c ℏ ℏ E N = m 4 π π c 3 ℏ ℏ M N = m 4 π π G M A = G m M r 2 .