Equipment:

• Styrofoam Ball in a Jar [Cabinet B2]

Demo:

The one gallon glass jar is filled with water. A Styrofoam ball is tethered inside. The jar is placed on the top of the demo table. The instructor moves the jar along the table with acceleration (see pictures). The ball moves in the direction of the acceleration.

Explanation:

In a car, when you accelerate forward there is an  opposite force that pushes you into the chair. Our first instinct is to think that the ball will move in the opposite direction. However, since the water has a greater density and mass it is forced to the back forcing the ball to move towards the direction of acceleration.