Question

A 485 kg sphere sits at 14.0 km due north of an 852 kg sphere. What is the force of gravity on the first sphere due to the second sphere? Compare this to the force of gravity on the second sphere due to the first sphere.

Answer 1

$F_{12}=F_{21}=G\frac{m_1m_2}{r^2}=$

$=6.67\cdot10^{-11}\cdot\frac{485\cdot852}{14000^2}=1.4\cdot10^{-13}(N)$