STEM PRACTICE AND EVIDENCE WORKBENCH
Calculate point-mass angular momentum before and after a radius change and audit conservation claims with a declared residual tolerance.
Review output
Load the worked example to inspect realistic inputs, or enter anonymous classroom or laboratory evidence. Results remain in this browser tab until you copy or download them.
Transparent method
For this bounded point-mass model, moment of inertia I equals mass times radius squared and angular momentum L equals I times signed angular velocity. Calculate initial and final L independently. Residual percent is absolute final minus initial divided by absolute initial times 100. Conservation is supported when that residual does not exceed the declared percentage tolerance. Supported means the entered yes-or-no claim matches the simplified calculation within tolerance. It does not prove zero external torque or validate the point-mass assumption. Compare the residual with measurement uncertainty and repeated trials. Inspect sign conventions, axis choice, mass distribution, apparatus friction, radius reference, timing, sensor calibration, and energy changes before drawing a physical conclusion.
Confirm the learning question, authoritative source, units, notation, response coding, model assumptions, and review threshold. Keep an unchanged copy of the original evidence and remove learner names or identifiers.
Run the worked example first, inspect every intermediate row, and compare it with a hand calculation, diagram, representation, or approved subject method. Correct input evidence before interpreting a flag.
Record the method, assumptions, units, classifications, and flagged rows. Verify the editable report independently, connect the numerical signal with learner reasoning, and document any teaching or laboratory decision outside this tool.
How to interpret the result
Use while planning or reviewing a simplified rotating point-mass investigation in which radius and angular speed are measured before and after a change. The table exposes both moments and the residual rather than returning only a claim. It does not calculate a rigid-body inertia, infer external torque, correct sensor bias, propagate uncertainty, establish isolation, or certify laboratory safety.
The constant-radius trial preserves mass, radius, and angular speed, so both angular momenta are 2 in compatible derived units. The contracting-radius trial changes radius from 0.8 to 0.4 while angular speed rises from 2 to 8, preserving 1.28. The measured-loss row differs beyond tolerance and correctly says no. The final values conserve momentum but the entered no claim is flagged.
For this bounded point-mass model, moment of inertia I equals mass times radius squared and angular momentum L equals I times signed angular velocity. Calculate initial and final L independently. Residual percent is absolute final minus initial divided by absolute initial times 100. Conservation is supported when that residual does not exceed the declared percentage tolerance.
Supported means the entered yes-or-no claim matches the simplified calculation within tolerance. It does not prove zero external torque or validate the point-mass assumption. Compare the residual with measurement uncertainty and repeated trials. Inspect sign conventions, axis choice, mass distribution, apparatus friction, radius reference, timing, sensor calibration, and energy changes before drawing a physical conclusion.
Do not use radius instead of radius squared, substitute tangential speed for angular speed without conversion, change the axis between measurements, drop a negative rotation sign, compare only angular speeds, divide residual by the final value silently, or describe agreement within tolerance as exact conservation. Draw the geometry, state the model, preserve units, and test uncertainty.
Learning boundary
This browser-local workbench applies only the disclosed rules. It cannot diagnose a learner, certify an experiment, establish assessment validity, or replace teacher, laboratory, curriculum, accessibility, and safety judgment.
Review checklist
Practical questions
No. Processing occurs in the current browser tab. Avoid personal information and retain authoritative records only in the approved school system.
No. It describes entered evidence under one disclosed rule. Review reasoning, uncertainty, access, and several evidence sources.
Treat it as an editable calculation aid. Show your own reasoning, cite required sources, and follow course and academic-integrity rules.
YOUR NIRMION
