arXiv:1501.02858
Using Tracker to understand toss up and free fall motion: a case study
Tracker video analysis for toss-up and free-fall motion
Research Digest
This paper is a classroom case for helping beginning physics students connect a real video of vertical motion with displacement-time and velocity-time representations. The useful classroom idea is not merely to show a video, but to let students measure, fit, and then model the motion so that acceleration due to gravity becomes an evidence-based claim.
Use It Tomorrow
Use a short toss-up or free-fall clip. Ask students to track the object, inspect the velocity-time graph, and explain why the slope stays nearly constant even though the direction of velocity changes.
Pedagogical Move
After analysis, ask students to build or compare a simple dynamic particle model. This shifts the task from reading a graph to explaining why the graph has that shape.
Student Agency
Frame the task so students work like young scientists: they choose or justify the variable to test, make a prediction, collect evidence, defend a claim, and decide how to improve the model or investigation.
Discussion Prompts
- What evidence does the model, video, or activity make visible?
- Which variable should students change first, and what should they keep constant?
- What claim can students make from the evidence, and what limitation should they acknowledge?
Reveal suggested answers
- Evidence: Tracker makes the toss-up motion visible as measured position-time data, velocity-time data, fitted curves, and an acceleration estimate.
- Variable: Change the time interval or fit region first; keep the scale calibration, coordinate direction, tracked point, and frame rate fixed.
- Claim: Students can claim that the object has approximately constant downward acceleration, while acknowledging video-tracking uncertainty and air resistance.