When photogates are used to study the motion of an object, the velocity and accelerations are calculated with a different algorithm than the algorithm used for motion detector data. The reason for this difference is that motion detector data is recorded with uniform time intervals. When studying accelerated motion with photogates, the time intervals are not uniform.

An excellent article describing this situation can be found in the April, 1997 issue of The Physics Teacher. The article written by William Leonard is entitled “The Dangers of Automated Data Analysis.”

The article describes a different way to calculate velocity and acceleration when photogates are used. This calculation is used in Logger Pro software, LabQuest App, Graphical Analysis, and our calculator-based software. Logger Pro help includes the detailed calculations on the page “Advanced Photogate Setup.”

See also:
How do Logger Pro, Graphical Analysis, LabQuest app, and Vernier Video Analysis calculate velocity and acceleration?
How can I compare my g measurements to a local value and improve their accuracy?