Remember Blue Marble? Well this is the sequel, Blue Marble 2, a Rube Goldberg style machine that moves the titular blue marble around a 2-D course via the power of potential energy. You probably won't watch it which is a shame because it really is worth a view, it's very clever. Some more info on the balloon air cannon part while I see how long a lunch break I can take without anybody saying anything (my previous record is 26 hours):
The air cannon with the balloon was a big challenge to make. The rubber band squeezes the balloon around the straw to release the air in a specific direction. Then the hardest part was to find how to stop the air and deliver it when I want. It was too difficult to put something like tape at the end of the straw because it was either too clingy or not enough.
The solution was to twist the balloon around the straw and block it in this position with a rope. In this position the air stays in the balloon until it untwists. I explain it because I think what exactly happened it's not easy to get when you see the video.
It's crazy how absolutely perfectly every part has to work for the blue marble to make it safely to the end of its journey. It's just like the moon landing, but with fewer giant leaps for mankind. "So zero." Personally I give it a solid hop over a crack in the sidewalk. "When I was younger I used to purposefully step on cracks when I was mad at my mom." Please don't ever tell her that, it'll break her heart.
Keep going for the video while I finally swallow the tiny square of Apollo 11 command module foil I've been saving for a special occasion.
Thanks to Gregory H, who agrees potential energy is cool, but sleeping on the couch all Saturday afternoon is even cooler.