PURPOSE: To demonstrate F = ma.

DESCRIPTION: A small mass hanging over a frictionless pulley provides the constant force which accelerates the dynamics cart between gates A and B. Using the photogate timing system, the time for the dynamics cart to travel from A to B can be measured, or the velocities of the dynamics cart at positions A and B can be measured using the 5 cm tab mounted on the dynamics cart. The accelerating force can be varied by adding additional masses, or dynamics carts of mass M, 2M, and 3M (2M + M) can be used. A careful measurement yields a result good to a few percent.

SUGGESTIONS:

REFERENCES: See instruction sheet for Photocell Gate Timer in Demonstration Reference File.

EQUIPMENT: Dynamics track, Data acquisition system with photocell gate timer system, dynamics carts of mass M and 2M, small masses, Pulley with frictionless cord, as photographed.

SETUP TIME: 10 min.

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