Vernier Tech Info Library TIL #1914

Question

My motion detector still reads 0.004 m after zeroing.

Answer

There is a bug in Logger Pro 3.6 and 3.6.1, when used with LabPro, where the motion detector can be zeroed, and reads zero in live readouts, but will read 0.004 m during data collection. This is enough to throw off certain energy calculations, such as the energy in simple harmonic motion lab in Physics with Vernier.

Workarounds include using a LabQuest, manually correcting the 0.004 m reading using a calculated column, or using Logger Pro 3.5.

To manually correct for the position error, do the following

1) Create a calculated column, e.g. "position rezero". The equation for this correction will be "Position - 0.004".
2) Modify the definition of the Potential Energy column definition so that the variable is "position rezero" instead of "position". (See the attached file as an example.)

The error is on the list of things to fix for Logger Pro 3.7, which is scheduled for release in the first quarter of 2009. To be notified of Logger Pro and other software releases, you can sign up for our Power User e-mail list at:
http://www.vernier.com/poweruser/

Created by: gastineau on November 04 2008
Last updated by: rsorensen on December 02 2008