Teach lesson
Pendulum: what controls the period?
Advanced inquiry in which students use the Pendulum remote lab to test whether initial angle or pendulum configuration (including soda-can positions) has the larger effect on period.
Learning Outcomes
Use the Pendulum remote lab to collect angle-time evidence from the lab or teacher-provided reference data.
Estimate pendulum period from repeated cycles or same-direction crossings.
Compare an angle sweep with a fixed-angle configuration comparison.
Write a claim-evidence-reasoning conclusion about what controls period in this lab.
Student activity preview
Activity Content
Preview only. In a class session, students can fill in responses and submit their work to the teacher.
Frame the investigation
9 min
A pendulum's period is the time for one complete oscillation. In this lab you can change the starting angle and the pendulum configuration, then observe the motion and download angle-time evidence.
Your investigation has two controlled parts:
1. Keep the configuration fixed and change the initial angle.
2. Keep the angle fixed and change the configuration.
Lab configurations
Use one variable at a time. The short pendulum changes effective length; the soda-can positions also change where the mass is located, so do not explain the result as "more mass" alone.
For a standard pendulum, what do you predict will happen to the period when the initial angle increases from 10 degrees to 30 degrees?
Which configuration do you expect to have the shortest period, and why? Use the idea of effective length or where the mass is located.
Use the remote lab deliberately
12 min
Lab strategy
Use the eight-row plan below unless your teacher assigns a shorter version:
- Angle sweep: standard pendulum at 10, 15, 20, 25, and 30 degrees.
- Configuration comparison: short, soda-can-up, standard, and soda-can-down at 15 degrees.
The standard 15-degree row counts in both parts, so the total is eight lab rows.
Open the Pendulum lab
Open the Pendulum lab from Teach.
Choose the pendulum configuration for the current row.
Set the initial angle for the current row.
Start observing and watch the angle-time graph.
If the lab lets you download CSV, XLSX, or PNG and you want to use them, you can; it is not required.
Estimate the period from repeated cycles or same-direction crossings.
If your session is demo-limited, record the limitation and use your teacher's provided reference data for unavailable rows.
Which plan best tests whether configuration affects period?
Record and process evidence
16 min
Fill all eight rows. Each row is one period estimate. In comparison, copy the label already shown (angle sweep or configuration comparison). In configuration and initial angle, copy the values already shown for that row. In period estimate, write the period in seconds you obtained: if you downloaded CSV/XLSX, you can estimate it by finding repeated same-direction zero crossings, or by timing several full oscillations and dividing by the number of oscillations. In evidence origin, write where the value came from, such as graph peaks, zero crossings, video chronometer, or teacher reference data. Use notes for any extra observation.
Pendulum period evidence
Enter one period estimate per row. Use seconds. If you use teacher-provided reference data because of demo limits, say so in the evidence column.
| Comparison | Configuration | Initial angle deg | Period estimate s | Evidence origin | Notes |
|---|---|---|---|---|---|
Explain how you estimated period from the lab evidence. Mention whether you used repeated oscillations, zero crossings, graph peaks, CSV/XLSX data, or a teacher-provided reference table.
Show one period calculation. For example, if five complete oscillations take 6.56 s, the period is 6.56 / 5 = 1.31 s. Use one row from your table.
Look for patterns
11 min
Before submitting your graph evidence, make two simple graphs from your table.
1. Angle graph: use only the standard-pendulum rows. Put initial angle (degrees) on the horizontal axis and period T (s) on the vertical axis.
2. Configuration graph: use the 15-degree rows. Put configuration on the horizontal axis and period T (s) on the vertical axis.
Each graph should have a clear title, axis labels with units where needed, and one plotted point for each table row used. Do not smooth the points into a perfect curve; your measured values may scatter by several percent.
Blank graph templates
Use these templates as a layout guide. Add your own measured points from the table; the figure intentionally does not show the result.
Graph or spreadsheet evidence
Submit evidence that supports your angle sweep and configuration comparison: an image or screenshot of your graph, a link to a spreadsheet, or a teacher-checked graph. If you cannot upload a file, describe what you put on each axis and which points appear.
Use the standard-pendulum rows to decide whether angle had a small, moderate, or large effect on period in your data. Cite at least two period values.
At 15 degrees, compare the configurations. Which configuration had the shortest period and which had the longest? What physical reason explains the difference?
Make the scientific claim
7 min
Which statement is best supported by this lab?
Write a claim-evidence-reasoning conclusion. Use this structure if it helps:
- Claim: Initial angle had a small/moderate/large effect, and configuration had a smaller/larger effect.
- Evidence: cite at least two angle-sweep periods and at least two 15-degree configuration periods.
- Reasoning: explain the pattern using effective length, mass position, and measurement uncertainty.
Extension
8 min
If you had more time, what additional row or repeat would most improve your conclusion? Explain whether it would reduce uncertainty, test a larger angle range, or separate mass from effective length better.