Question

Two objects have masses of `22 MG` and `23 MG`. How much does the gravitational potential energy between the objects change if the distance between them changes from `25 m` to `7 m`?

Please let me know the answer.... Thank you

Answer 1

`-0.0035J`, rounded to four decimal places

Explanation:

Gravitational Potential energy between two bodies of mass `M_1and M_2` with distance between their centers being `r` is given as

`U=-G(M_1M_2)/r`
where `G` is Universal Gravitational constant `=6.67408 xx 10^-11 m^3 kg^-1 s^-2`.
`-ve` sign shows that it is bound system.

`DeltaU=U_"final"-U_"initial"`
Inserting given values we get
`DeltaU=-G(M_1M_2)/7-(-G(M_1M_2)/25)`
`DeltaU=-G(M_1M_2)(1/7-1/25)`
`DeltaU=-6.67408 xx 10^-11(22xx10^3xx23xx10^3)(18/175)`
`DeltaU=-0.0035J`, rounded to four decimal places