The linear air track is a long metal tube with tiny holes in. Air from the outflow of a vacuum cleaner is blown down the tube and comes out through the holes, leaving a layer of upwardly mobile air on which gliders float.
I use it in conjunction with light gates to try to show conservation of (linear) momentum but also to illustrate Newton's First Law. Once you get the glider moving, it does not require a constant application of force to keep it going. It will keep going in a straight line at a steady speed until it hits the other end and an external resultant force acts on it. Then it will change direction and come back in a straight line at a steady speed etc. Aristotle thought that objects needed force on them all the time just to keep them going at a steady speed. His problem was that he inhabited a world of friction.
The odd thing about our vacuum cleaner is that the tube is kept inside. You have to pop the black handles at the top of the silver drum and list the top off carefully.
Then screw the hose onto the outflow of the vacuum cleaner as shown below. It connects to the linear air track as shown in the top photo. When you put it away, coil the hose so that it doesn't get crushed when you put the lid back on.
