Using a simple spreasheet, I’ve found how the force of gravity on the balloon changes over time. The gravitational force changes because the balloon moves farther and farther away from the earth.

If you look at the formula for Gravitational force, you’ll notice that little R squared on the bottom. This is the distance between the two objects (M1 & M2). So, as that r distance goes up, the force of gravity goes down. That being said, the 50,000m the balloon flys for changes the gravitational force quite a bit. Now, looking at my spreadsheet (attached), the change in the gravitational force is almost half a newton. Not a large number, but still a significant change all the same. All the best,

-B.