The two bodies with masses
and
attract each other with a force
.
Where
.
Apply formula
.
.
Find the work required to propel a
space vehicle out of earths gravitational field.

Here
is the mass of the earth,
is mass of the space vehicle,
is the radius of earth and
.





Substitute
,
,
and
in
.




.
The work required to propel a
space vehicle out of earths gravitational field is
.
The work required to propel a
space vehicle out of earths gravitational field is
.