Starter track
Follow the authored sequence, or switch to recap mode for a faster review of the same path.
Start with one source mass creating a field and potential well, then use that same gravity model to explain circular speed, orbital periods, and the escape threshold.
Entry diagnostic
Reuse the gravity-fields quick test and the existing field-to-potential checkpoint to decide whether to start from the source-mass field basics or jump straight into circular-orbit balance.
Check the gravity bridge before you enter orbits
Motion and Circular Motion is the authored prerequisite for Gravity and Orbits. Vectors and Components opens this track and sets up the rest of the path. Nothing is hard-gated here; this is simply the clearest setup before the track opens.
Uses the same local-first quick tests, checkpoint challenges, and track history already saved in this browser.
Check whether inward field direction, inverse-square drop, and source-versus-probe roles are already stable.
No saved quick-test result yet.
Starting from Axis 1 m, move the probe to the doubled-distance case on the same horizontal line so phi is about half as deep and the field magnitude is about one quarter as large.
No saved checkpoint attempt yet.
About this track
Keep the first scan focused on the next lesson. Open the authored rationale and shared-framework notes only when you need them.
Why this order
Gravitational Fields comes first because the orbit and energy ideas are harder to trust if the source-field picture is still fuzzy. Gravitational Potential and Potential Energy keeps the same one-mass model while turning the field into a well-depth story, Circular Orbits and Orbital Speed uses that same inward pull for stable sideways motion, Kepler's Third Law and Orbital Periods turns the circular case into honest year-length comparisons, and Escape Velocity closes by showing what changes when the launch is no longer bound.
Shared concept pages
Compare mode, prediction mode, quick test, worked examples, guided overlays, challenge mode, and read-next cues stay on the concept pages. The track only decides the guided order and the next recommended stop.
Guided path
Checkpoint cards reuse the authored challenge entries already living on the concept pages.
See how one source mass creates an inward gravitational field, how source mass and distance set the field strength, and how a probe mass turns that field into force without changing the field itself.
Start here before moving into Gravitational Potential and Potential Energy.
See one source mass create a negative potential well, compare how potential and potential energy change with distance, and connect the downhill slope of phi to the gravitational field on the same live model.
Builds on Gravitational Fields before setting up Circular Orbits and Orbital Speed.
Starting from Axis 1 m, move the probe to the doubled-distance case on the same horizontal line so phi is about half as deep and the field magnitude is about one quarter as large.
Finish Gravitational Potential and Potential Energy first. This checkpoint ties together Gravity fields and Gravity potential through Half the potential, quarter the field.
Pause here after Gravitational Potential and Potential Energy before moving into Circular Orbits and Orbital Speed.
See why a circular orbit needs the right sideways speed, how gravity supplies the centripetal acceleration, and how source mass and radius together set orbital speed and period on one bounded live model.
Builds on Gravitational Potential and Potential Energy before setting up Kepler's Third Law and Orbital Periods.
Compare circular orbits around one source mass and see why larger orbits take longer: the path is longer, the circular speed is lower, and the same live model makes the period law visible without hiding the gravity-speed link.
Builds on Circular Orbits and Orbital Speed before setting up Escape Velocity.
Open compare mode, keep the same source mass in both setups, set Setup A to the inner circular orbit, and set Setup B to the much wider circular orbit so Setup B has the longer year.
Finish Kepler's Third Law and Orbital Periods first. This checkpoint ties together Orbital speed and Orbital periods through Inner year vs outer year.
Pause here after Kepler's Third Law and Orbital Periods before moving into Escape Velocity.
Launch outward from one bounded gravity source and see how source mass, launch radius, and total specific energy decide whether the object escapes or eventually returns.
Capstone step after Kepler's Third Law and Orbital Periods.
Starting from High but bound, raise the launch just to the threshold case at the same source mass and launch radius so the total specific energy is about zero and the finite turnaround disappears.
Finish Escape Velocity first. This checkpoint ties together Gravity potential, Orbital speed, Orbital periods, and Escape speed through Remove the finite turnaround.
Final checkpoint that closes the authored track after Escape Velocity.
