You know when a car suddenly accelerates you are pushed back into your seat? And when the car brakes you are pulled forward?
Well, did you know that a floating balloon in the car moves in the opposite directions? So when the car brakes, the balloon in your hand will float backwards while you move forwards in your seat.
It’s demonstrated perfectly in the video below and just makes no sense whatsoever. Why does the balloon move against the forces that act on our bodies during acceleration/deceleration?
Luckily for us the videomaker explains it perfectly and the answer is incredibly simple.
So during acceleration the same force that pushes us back into our seats is also pushing all the air in the car to the back, and as the helium in the balloon is lighter than air, it is being pushed out of the way i.e. forwards. Simples.
On a similar note but also in a different world altogether, this is how accelleration does not behave. The viewers comment shown give the best possible hypothesis. I almost posted a link to the video but I was afraid that watching it would actually lead to a lowering of our IQs so decided against it for health reasons. If you have no idea which video this image is from then I congratulate you and urge you not to look into it any further.
The Gazebo Effect 