Static Equilibrium Progression (thoughts and examples)

Here is a progression of Static Equilibrium problems that I think may be useful:

The rationale here is that with the 1st set of problems, students can proceed by first finding numeric values for components of the angled tension force using trigonometry, and then they can apply reasoning about net force.

In the 2nd set of problems, students can first apply reasoning about net force to determined the components, and then triangle geometry to determine the magnitude and angle. The reasoning in these first two is more “serial”, in that you either do some physics reasoning first and then some triangle geometry reasoning (or vice versa).

Only when we get to the third set do students have to do more integrated thinking — having to do more parallel or back-and-forth reasoning about physics and triangle geometry.

In my experience, the default static equilibrium problems of this genre look more like the 3rd one, but this may not be a great starting place for students.

imageScreen Shot 2019-10-24 at 6.01.16 AMScreen Shot 2019-10-24 at 6.01.22 AM

Useful Logger Pro File: Motion Detector with Multiple Representations

Here is useful Logger Pro File I made for using a motion detector with a cart on a 1.2 m track.

This video show cases some of its features, which are accessed on different pages of the file.

A slightly updated version can be found here at this link. It has some additional adornments with speedometers to help make connections to vectors, but I fear that some of pages are now too busy.

Also, if you are looking for a quick tutorial on how to make motion diagrams using animated displays, here you go.

I made this for a couple reasons:

  1. Motion diagrams are a pretty cool feature of motion detectors that most people don’t know about or use.
  1. I don’t usually like the default file that opens up when you attach a sensor.
  2. I don’t like having to make lots of different files for different labs.
  3. I wanted a file that my students could use any time they use a motion detector with a cart on track.
  4. I wanted a file that started simple a became more sophisticated / complex
  5. I wanted specific pairings of representations that would support understanding beyond the standard stacks of kinematics graphs.

Finally, I hope to get around to making a similar file that has been adjusted properly for use on the 2.2 m track, and another one that will be adjusted for tracking large objects. The adjustments needed are mostly to

Make sure the scale of the Animated display is correct and matches the graphs.

Blog at

Up ↑