We need to use the formula E_("P") = - frac(G M m)(r)EP=−GMmr; where E_("P")EP is the gravitational potential energy, GG is the gravitational constant, MM and mm are the masses of the two objects, and rr is the distance between their centres.
Let's calculate the gravitational potential energy for our case.
rr will be the difference between the two distances:
Rightarrow E_("P") = - frac(6.67408 times 10^(-11) " m"^(3) " kg"^(- 1) " s"^(- 2) times 6 " MG" times 9 " MG")(110 " m" - 320 " m")⇒EP=−6.67408×10−11 m3 kg−1 s−2×6 MG×9 MG110 m−320 m
Rightarrow E_("P") = - frac(6.67408 times 10^(-11) " m"^(3) " kg"^(- 1) " s"^(- 2) times 6000 " kg" times 9000 " kg")(- 210 " m")⇒EP=−6.67408×10−11 m3 kg−1 s−2×6000 kg×9000 kg−210 m
Rightarrow E_("P") = frac(6.67408 times 10^(-11) " m"^(2) " kg"^(- 1) " s"^(- 2) times 5.4 times 10^(7) " kg"^(2))(210)⇒EP=6.67408×10−11 m2 kg−1 s−2×5.4×107 kg2210
Rightarrow E_("P") = frac(0.0036040032 " kg m"^(2) " s"^(- 2))(210)⇒EP=0.0036040032 kg m2 s−2210
Rightarrow E_("P") = 0.00001716192 " kg m"^(2) " s"^(- 2)⇒EP=0.00001716192 kg m2 s−2
Rightarrow E_("P") = 1.72 times 10^(- 5) " kg m"^(2) " s"^(- 2)⇒EP=1.72×10−5 kg m2 s−2
therefore E_("P") = 1.72 times 10^(- 5) " J"
Therefore, the gravitational potential energy between the two objects is 1.72 times 10^(- 5) " J".