Two objects have masses of $9 MG$ and $5 MG$ . How much does the gravitational potential energy between the objects change if the distance between them changes from $500 m$ to $20 m$ ?

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Answer 1 · 2017-03-05T21:24:40

$7.488xx10^-6N$

The equation for gravitational potential energy (G.P.E) between two bodies is

$U = G(m_1m_2)/r^2$

where $U$ is G.P.E, $m$ is the mass, and $r$ is the distance. $G$ is known as the gravitational constant and is approximately $6.67xx10^-11$ .

Putting in values that we know, the initial G.P.E is

$U = 6.67xx10^-11 xx (9xx10^3xx5xx10^3)/500^2 = 1.2xx10^-8N$

and the final G.P.E is

$U = 6.67xx10^-11 xx (9xx10^3xx5xx10^3)/20^2 = 7.5xx10^-6N$

so the total change in G.P.E is

$7.5xx10^-6 - 1.2xx10^-8 = 7.488xx10^-6N$

Two objects have masses of 9 MG9 MG and 5 MG5 MG. How much does the gravitational potential energy between the objects change if the distance between them changes from 500 m500 m to 20 m20 m?