Air Track - Newton's Second Law
To demonstrate F = ma.
Air track, photocell gate timer system, gliders of mass M and 2M, small masses with audiotape frictionless cord, as photographed.
distance between them. You must therefore hold the glider so that the tab interrupts the photocell light beam immediately when
A small mass hanging over a frictionless pulley provides the constant force which accelerates the glider between gates A and B. Using the photogate timing system, the time for the glider to travel from A to B can be measured, or the velocities of the glider at positions A and B can be measured using the 5 cm tab mounted on the glider. The accelerating force can be varied by adding additional masses, or gliders of mass M, 2M, and 3M (2M + M) can be used. A careful measurement yields a result good to a few percent.
Information Sheet. B. Saelman, Some Notes on Newton's Second Law of Motion, AJP 25, 584-585 (1957). ◙James L. Anderson, Newton's first two laws of motion are not definitions, AJP 58, 1192-1195 (1990).