First of all, if it's filled with hot air, then there's no deflated balloon.
If a weight of 8,000N is raised to an altitude of 1,000 meters,
then 8 million Joules of work has been done.
Gravity does the work. The hot air doesn't.
If you filled the same balloon with the same hot air on the Moon,
the balloon would just lay there on its side on the lunar regolith
and look ridiculous, like some kind of enormous cloth light bulb.
The same hot air couldn't budge it an inch.
