This balloon activity is a simple but neat way to demonstrate friction. Similar to an old balloon propeller experiment Travis tried, it illustrates Newton’s third law (that for every reaction, there is an equal and opposite reaction). So when the air from the balloon is allowed to escape, the it propels the CD forward. Consider it for a quick science class if you’re homeschooling this week!
I raided my old CD binder for the project, which had the kids immediately intrigued. This is not technology they see often anymore.
Hot glue a pop-top water bottle cap to the middle of the CD, making sure the seal is air-tight.
Fit a balloon over the bottle cap, then blow through the hole in the bottom of the CD to inflate the balloon. This definitely takes some lung power!
Immediately seal the pop-top. Place the balloon on a flat surface, and lift the pop-top. As the air rushes out, your balloon will go forward, which had big wow factor every time.
We never managed to create enough energy to have the CD actually lift and hover, but please share in the comments if you do! We did get it to zoom, though, which you can see in this quick clip: