STEM REASONING AND EVIDENCE WORKBENCH
Calculate signed closing velocity and future meeting time for two constant-velocity objects on one declared axis.
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
Set xA at zero and xB at positive separation d at time zero. With constant signed velocities, xA equals vA t and xB equals d plus vB t. Their signed closing velocity is vA minus vB. When it is positive, solve xA equals xB to get t equals d divided by closing velocity. Zero or negative closing velocity gives no future meeting. Supported means both the signed relative velocity and the meeting condition agree with the entered model. A negative closing value describes increasing separation under this ordering; it should not be converted into a negative or positive meeting time. Draw both position-time lines and inspect their slopes and intersection to confirm the algebra.
Confirm the question, approved source, units, notation, signs, response coding, model assumptions, and review threshold. Keep an unchanged copy of measurements or learner evidence.
Run the worked example, inspect every intermediate row, and compare the result with a hand calculation, diagram, representation, periodic table, or approved laboratory method.
Record the method, assumptions, uncertainty, units, classifications, and flagged rows. Verify the editable report independently before instruction, assessment, or laboratory use.
How to interpret the result
Use for one-dimensional catch-up or approaching scenarios where learners need to distinguish relative speed from an individual speed and decide whether a future meeting exists. The model assumes constant velocities and one initial ordering. It does not model acceleration, curved routes, changing frames, reaction time, collisions, timetables, uncertainty, or real travel safety.
An object at 70 km/h closes on one at 40 km/h from 30 km behind at 30 km/h and meets after one hour. Opposite signed velocities 50 and negative 30 close a 120 km gap at 80 km/h in 1.5 hours. Equal velocities never close the gap. A receding case with closing velocity negative 15 has no future meeting, so a four-hour claim is flagged.
Set xA at zero and xB at positive separation d at time zero. With constant signed velocities, xA equals vA t and xB equals d plus vB t. Their signed closing velocity is vA minus vB. When it is positive, solve xA equals xB to get t equals d divided by closing velocity. Zero or negative closing velocity gives no future meeting.
Supported means both the signed relative velocity and the meeting condition agree with the entered model. A negative closing value describes increasing separation under this ordering; it should not be converted into a negative or positive meeting time. Draw both position-time lines and inspect their slopes and intersection to confirm the algebra.
Do not add speeds automatically, discard direction signs, divide by one object speed, use initial distance from a different reference point, report a negative time as a future event, or mix kilometres per hour with metres per second. Declare the axis, write both position equations, inspect closure, and substitute the result back.
Learning boundary
This browser-local workbench applies only the disclosed rules. It cannot diagnose a learner, certify an experiment, establish a chemical structure, 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 school-approved system.
No. It describes entered evidence under one disclosed rule. Compare several evidence sources and ask for reasoning before drawing a conclusion.
Treat it as an editable calculation aid. Show your own reasoning, cite required sources, and follow the course method and academic-integrity rules.
YOUR NIRMION
