PURPOSE: To demonstrate constant velocity and uniform acceleration using an air track.

DESCRIPTION: All gliders are equipped with a 5 cm tab which interrupts the light beam when passing through the photocell gate. The timing system can be set to measure the time a tab takes to move through the gate or the time taken for the glider to move from gate A to gate B (not B to A). The timer can be set at full scale ranges from 99.9 ms through 999 seconds for a range of applications.

Pushing a glider along the track illustrates constant velocity. Gliders can be connected to a mass hanging over a pulley at the end of the air track, or the air track can be tilted, to illustrate uniform acceleration. Masses of 1, 2, and 3 units can be used, or the acceleration can be varied by using different masses hanging over the pulley.


REFERENCES: (PIRA 1C10.25) An instruction sheet for the photocell gate timer is available in the Demonstration Reference File.

EQUIPMENT: Air track, gliders, photocell gate timer system, small accelerating masses with audiotape frictionless cord, as photographed.

SETUP TIME: 5 min.

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