STEM PRACTICE AND EVIDENCE WORKBENCH
Calculate friction coefficients and propagated force uncertainty, then audit learner ratios against an explicit review 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
Coefficient mu equals friction-force magnitude divided by normal-force magnitude. For independent small uncertainties, estimated coefficient uncertainty equals mu times the square root of the squared relative friction uncertainty plus the squared relative normal uncertainty. The learner check uses the entered percentage tolerance and a small numerical floor. Supported means the learner coefficient agrees with the raw ratio within the selected tolerance. The uncertainty column describes measurement precision under one propagation assumption; it is separate from the learner tolerance. Compare repeated trials, inspect whether uncertainty intervals overlap, and decide whether a mean, regression, or separate static and kinetic analysis is justified.
Confirm the question, source, units, notation, response coding, model assumptions, and review threshold. Keep an unchanged copy of the original evidence.
Run the worked example, inspect every intermediate row, and compare it with a hand calculation, diagram, representation, or approved subject method.
Record the method, assumptions, units, classifications, and flagged rows. Verify the editable report independently before educational or laboratory use.
How to interpret the result
Use after force measurements have been collected and the contact regime is known. The workbench makes the division and uncertainty contribution visible across repeated surfaces or loads. It does not identify a material, decide whether motion has started, correct a sensor baseline, fit a best coefficient, or prove that friction is proportional to normal force.
The first three fictional rows give coefficients 0.30, 0.30, and 0.25 from their friction-to-normal ratios. Their force uncertainties propagate into coefficient uncertainty through the ratio rule. The review row has five newtons of friction and 25 newtons normal force, so the expected coefficient is 0.20 rather than the entered 0.25.
Coefficient mu equals friction-force magnitude divided by normal-force magnitude. For independent small uncertainties, estimated coefficient uncertainty equals mu times the square root of the squared relative friction uncertainty plus the squared relative normal uncertainty. The learner check uses the entered percentage tolerance and a small numerical floor.
Supported means the learner coefficient agrees with the raw ratio within the selected tolerance. The uncertainty column describes measurement precision under one propagation assumption; it is separate from the learner tolerance. Compare repeated trials, inspect whether uncertainty intervals overlap, and decide whether a mean, regression, or separate static and kinetic analysis is justified.
Do not divide normal force by friction, substitute weight without checking the free-body model, mix units, combine static and kinetic data, enter percentage uncertainty as an absolute force, round before division, or treat one coefficient as universal. Inspect calibration, direction, surface condition, loading history, and repeated measurements.
Learning boundary
This browser-local workbench applies only the disclosed rules. It cannot diagnose a learner, certify an experiment, or replace teacher, laboratory, 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
