Didn't think a balloon could rock your world? Think again.
When you have a balloon floating in a car and you start driving forward, which way does the balloon move? In a new episode of the YouTube series Smarter Every Day, host Destin Sandlin shows us that the balloon doesn't do what you might expect.
Helium in the balloon is lighter than air around it in the car. So, as the car accelerates, air sloshes back while the helium actually pushes the balloon forward, illustrating an interesting principle of fluid dynamics. Just check out the video above.
It may sound like an obvious physics phenomenon -- after all, Sandlin's five-year-old kid in the video got it -- but watching the experiment play out is quite fascinating.