GENERAL INSTRUCTIONS: AIR TRACKS AND AIR TABLES
Air tracks and tables allow mechanics experiments to be performed with greatly reduced friction. In all but the most precise experiments drag forces on the air table can be ignored. The moving bodies being studied are supported on a thin film of air provided by air flow from many small holes drilled in the supporting surface. A vacuum cleaner operated as a blower forces air under pressure through these holes. Bodies for use on air tracks are called "gliders." Bodies for use on air tables are called "pucks" (a term obviously borrowed from hockey).
Valves in the air supply system allow the air to be quickly turned on or off. This is useful for quickly stopping the glider or puck motion, freezing them in place for taking data on "final" position.
The aluminum air track surface usually has a V-shaped profile to keep the gliders on the track. The gliders are equipped with spring-steel bumpers at each end, and the track has similar bumpers at each end. These are highly elastic, so there is very small energy loss on collision. If an inelastic collision is desired, the bumper surfaces may be covered with rubber, putty, double-sided cellophane tape, or Velcro fabric strips.
The table surface is a plastic composition board laminated to a honeycomb inner structure of heavy treated paper. This construction gives lightness and strength, and preserves the surface flatness. A taut-wire bumper surrounds the table perimeter. The pucks are plastic, usually round, but irregularly shaped pucks are also available.
Reproducible initial velocities may be obtained with rubber-band launchers designed so that the rubber band may be pulled back the same distance each time. Known horizontal forces may be applied by a length of 1/4 inch wide magnetic recording tape connected to the puck or glider, passing over an air pulley and then to a weight hanging from the other end of the tape.
DATA COLLECTING METHODS:
Air tracks are usually equipped with a spark wire arrangement and a calibrated variable rate spark source, producing sparks at known time intervals. A long wire runs the length of the track, and a short bridging wire on a glider is arranged so that one end of it passes near to (but not touching) the long wire. The other end of this bridging wire passes near to a portion of the metal track over which has been stretched a long waxed paper recording tape. As the glider moves, sparks jump from the long wire, to the bridging wire on the glider and then through the waxed paper to the metal track. These sparks melt a spot of wax on the paper, permanently recording the glider position at that time. The waxed tape record may then be removed completely for analysis.