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.

Well someone beat me to it. They solved for the ascent rate. Mad props to them because it would’ve taken me much longer.

http://www.wired.com/wiredscience/2012/05/angular-size-and-the-height-of-a-space-balloon/

Now lets see If our data lines up with the data of the launch. The wired article puts the velocities around 3.2 and 4.5 m/s^2.
If we make that into a velocity with an acceleration, 4.5-3.2/600, we get a very small acceleration. From that, I made a simple spreadsheet, and it puts the pop point at around 90 minutes.
On it’s voyage back down lets put the terminal velocity at 193kmph, this puts the total voyage time just over 2 hours. It may be that the acceleration of the balloon is a lesser value. Or maybe the balloon slows down as it rises, but I can’t prove or disprove that. As the balloon gets farther away, the Fg slowly decreases, but I’m not sure how the Force of the balloon changes. Anywho, That all I have for now, all the best, -B.

I tried setting up a ratio of Control f/s over control Pixels/s to Flight f/s (Unknown) to flight P/s. I didn’t work. Here’s the data I got:

I’ve created a SpreadSheet that computes, based on the pixels count of a man’s height and the track radius, a good range of speeds, centripetal accelerations, track length, Car velocity, forces on the cable and which types of rope or cable have the ability to handle the force. This spreadsheet can also be used for any centripetal acceleration problem for a video. Simple plug in the Constants Pixel height, Your guess of the Constants Meter height (Fill in cell B2 and the spreadsheet populates in steps of.05), and the track radius pixel length. Then It shows neat facts like your track radius in meter, and track length. From there, plug in a period time and a mass, and you have object velocity and centripetal acceleration, along with forces.

Using the above spreadsheet, I’ve analysed this video of a RC claiming to be going 200 mph. Plugging in the variables mentioned above, I have found that there actually is a pretty good chance that car was going around 200 miles per hour. You stay classy internet

-B.

I tried another method of finding the height today. I compared a pictures who’s subjects were similar lengths in pixels. I then compared there actual length to height off the ground. It didn’t work. I calculated that the balloon went down. Oh well. It looks as if I must resort to Focal Length. Which I need some serious help on. Cool beans.

Edit: took a look at focal length stuff.

[distance to object (mm) = focal length (mm) * real height of the object (mm) * image height (pixels)] / [object height (pixels) * sensor height (mm)]

The thing I don't understand is how I find the focal length to begin with. Or the sensor height

Indeed I do believe it is going at the said 200 Miles per hour that they stated. For further reference, please enjoy my spreadsheet below. This also means the height of the man stooping is five foot, three and three fifths inches tall.  Snazzy. Now the question is how much this bugger weights, but I don’t think I’ll be able to find that out based on the video. That also means that the material they used can also not be determined. Very well. You stay classy internet,

-B.