Vernier Hooks Law Flag

Motion Sensor Plate Flag

Description

At Eckerd, we have a lab experiment using a Vernier DFS and motion sensor to determine a spring constant using Hook's Law. If you have a force sensor connected to a spring and move it up and down over a motion sensor, you can create a graph of force vs. distance. Per Hook's Law the slope of the fitted line is the spring constant. In order to give the motion sensor a good surface to pick up, we used a paper plate attached to a mass hanger and held the mass hanger to the force sensor as we moved it up and down. 3D printed version attaches directly to the end of the force sensor mounting rod.

I have also created a bolt on version of this flag. We have been finding that when students accidentally drop the flag, the press fit hub can break off. The bolt on version uses a .5" 1/4-20 bolt. Just unscrew rod and screw in flag.

Close-Up of Plate Flag Hub

Construction

The press fit Flag is 6" in diameter. The center mounting hub is designed to flex as you insert the end of the mounting rod, hopefully absorbing and 3D printer tolerances (my first attempt the hub was too tight). It takes about 2 hrs of print time at medium speed.

My new design has a stronger hub that requires carefully pressing in a 1/4-20 bolt that then can be screwed directly into the force sensor.

Force Sensor Mounted to Flag and Hook's Law Experiment Set-Up

Old Way of Performing Experiment vs. New Way

New Bolt on Version

Physics Instructional Resource Association (PIRA) http://physicslearning2.colorado.edu/Pira