Two objects have masses of 6 MG6MG and 9 MG9MG. How much does the gravitational potential energy between the objects change if the distance between them changes from 320 m320m to 100 m100m?

1 Answer
Aug 3, 2017

E_("P") = 1.72 times 10^(- 5) " J"EP=1.72×105 J

Explanation:

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=6.67408×1011 m3 kg1 s2×6 MG×9 MG110 m320 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=6.67408×1011 m3 kg1 s2×6000 kg×9000 kg210 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=6.67408×1011 m2 kg1 s2×5.4×107 kg2210

Rightarrow E_("P") = frac(0.0036040032 " kg m"^(2) " s"^(- 2))(210)EP=0.0036040032 kg m2 s2210

Rightarrow E_("P") = 0.00001716192 " kg m"^(2) " s"^(- 2)EP=0.00001716192 kg m2 s2

Rightarrow E_("P") = 1.72 times 10^(- 5) " kg m"^(2) " s"^(- 2)EP=1.72×105 kg m2 s2

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".