Gm1m2/L²=m1(2π/T)²r1 r1=m2*L/(m1+m2)联立以上两式得：Gm1m2/L²=m1(2π/T)²*m2*L/(m1+m2)G/L²=(2π/T)²L/(m1+m2)化简可得5.的T，再变形可得6.的结论。
