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AP03 · SCIENCE THROUGH EVIDENCE

AP Physics 1: algebra-based mechanics

68 original destinations cover all eight content units and two full-course synthesis investigations, with cumulative mixed assessment and a retained evidence portfolio. Authored coverage does not certify learner mastery, actual hands-on laboratory time or AP authorization.

This is the course outline. Open a unit to choose a lesson; every lesson opens on its own page. Explanations and experiments live inside those lesson pages.

Preparation and course boundaries

Preparation: Algebra, right-triangle geometry, signed graph slopes and geometric areas. No calculus is required; use the supplied data or bounded CPU investigations before attempting supervised practical work.

Course outcome: Across mechanics and fluids, connect motion representations with system-specific force models, derive constraints, infer parameters and test assumptions using explicit evidence boundaries.

All lessons are directly accessible. Reused foundation explanations are identified where relevant; completing a different course does not award this course's evidence. The 68 registered lessons keep separate predictions, captures, practice responses and reflections.

Unit 1 — Kinematics8 lessons

Explain, predict and test motion using vectors, graphs, algebra and supplied-data investigations.

Specify a frame before measuring motion

Keep observer velocity at 1 m/s and compare origins −2 and +2 m. Record initial and final positions and their difference. Next hold origin fixed and compare observer velocities 0 and 2 m/s. Explain why the first intervention translates the curve while the second changes its slope.

Distinguish a displacement vector from a route

Compare (3,4), (−3,4) and (0,4). Sketch each route and direct displacement. Find when the route distance equals the displacement magnitude and explain the equality geometrically. Test the zero-vector case rather than assigning it a physical angle.

Infer velocity from a position graph with uncertainty

Hold acceleration at 1 m/s². Compare half-windows 1, 0.5 and 0.25 s; record the velocity estimate and worst-case bound. Explain why the exact midpoint velocity stays fixed while the measured estimate changes. Repeat with negative acceleration and retain the same error signs.

Reconstruct displacement and distance from velocity

Compare (v₀,a)=(3,−1), (4,−1), and (−3,1). Calculate each area before checking the table. Locate any interior reversal and explain the boundary case where velocity reaches zero exactly at 4 s. Record both displacement and distance.

Derive the equations and test their assumptions

Choose total velocity change 8 m/s and elapsed time 4 s. Derive all three displacements from geometric areas before using the output. Then halve elapsed time while keeping the velocity change fixed. Distinguish the change in average acceleration from the change in displacement.

Connect projectile components through one clock

Hold upward velocity at 8 m/s and compare horizontal components 2,4 and 8 m/s. Then hold the horizontal component fixed and vary the vertical component. Use ratios to test the range, flight-time and height equations. State the condition needed for the return-time formula.

Translate a projectile between inertial observers

Fix ground horizontal velocity at 5 m/s and compare observer velocities −3,3 and 5 m/s. Then choose a ground horizontal velocity below the observer velocity to make relative motion negative. Check that apex height, return time and vertical landing velocity remain unchanged.

Infer a parameter and challenge it with unused evidence

Compare sampling intervals 1,0.5 and 0.25 s at the same position bound. Record the number of selected observations, acceleration estimate, bound and held-out residual. Then change the error bound. Explain why passing a held-out check is conditional and why correlated calibration error is not eliminated by more points.

Unit 2 — Force and translational dynamics10 lessons

Choose a system, construct interaction diagrams, derive motion constraints and test force models with original evidence cases.

Choose a system and locate its center of mass

Compare equal masses, a heavier left mass and a heavier right mass. Calculate the weighted offsets for each case. Find two different mass pairs with the same center and explain the shared mass ratio. State which body-to-body forces become internal when both objects enter the system.

Draw forces on one object without double counting

Compare pull angles 0°,30° and 60° at 20 N. Draw the three actual interaction arrows before using the ledger, then resolve components in equations. Check the vertical sum and the horizontal sum separately. Predict what would break if an unbounded pull lifted the cart off the track.

Locate Newton’s third-law partners on different bodies

Compare equal masses and a 3:1 mass ratio. List each interaction force and the acceleration of its recipient. Multiply accelerations by their masses and verify cancellation for the whole system. Explain why this is not cancellation within either individual diagram.

Separate equilibrium from being at rest

Begin with equal forces and verify constant nonzero velocity. Increase only the leftward force, then only the rightward force. Predict whether the object initially speeds up or slows down and whether it reverses within 2 s. Explain the motion using signs rather than “positive force means forward motion.”

Infer mass from a force–acceleration relationship

Hold mass fixed while varying offset; compare slopes using two well-separated data points. Then hold offset fixed and change mass. Explain which graph feature changes in each intervention. Write a calibration test that could distinguish a sensor offset from an actual constant opposing force.

Distinguish gravitational field, mass and weight

Compare center distances 1,2 and 3 reference radii at fixed central mass. Then double central mass at fixed radius. Test the ratios without recalculating G. Record field and weight separately. Explain why the altitude column is always one less than the center-distance ratio.

Decide whether static friction can maintain rest

At normal force 40 N, compare pushes 8,20 and 22 N. State the regime before calculating friction. Then hold the push at 22 N and increase normal force to 60 N. Explain why increasing the maximum allowed friction need not mean the actual friction reaches that maximum.

Infer a spring constant and retain the restoring sign

Compare positive, zero and negative extension at fixed k. Then compare two spring constants at the same extension. Fit a slope from two table values and distinguish the spring’s force from an external holding force. Explain why a line through total length would need a nonzero intercept.

Identify the real inward force in circular motion

Find a feasible and an infeasible setting pair. Predict the tension ratio after changing only speed, then only radius. Derive the maximum permitted speed symbolically and compare with the ledger. Explain why an outward force arrow would be inappropriate in the inertial-frame free-body diagram.

Solve coupled carts and test the system boundary

Compare(2,3) kg with(3,2) kg and retain both free-body diagrams. Then add mass only to the trailing cart and predict changes in acceleration and tension separately. Verify both individual equations and the combined equation numerically. State what independent observation could falsify the shared-acceleration assumption.

Unit 3 — Work, energy and power8 lessons

Build signed work and system-energy ledgers, test accessible states and compare energy transfer rates with explicit constraints.

Compare kinetic energy without losing the frame

Compare observer velocities−2,0,2 and 4 m/s at fixed mass. Predict the energy from relative velocity before checking. Then double the mass without changing either velocity. Explain the separate linear and quadratic dependencies.

Determine the sign of work from force and displacement

Hold the force at 12 N and compare angles 0°,60°,90°,120° and 180°. Predict signed work, then final kinetic energy and speed. Explain why a backward component reduces energy even while the object still moves forward.

Use a force-position graph to calculate work

Compare endpoint pairs(8,−4),(4,−4) and(−8,−4) N. Sketch the line and signed areas first. Use both geometric splitting and the trapezoid expression. Check that the final kinetic energy equals 50 J plus the calculated work.

Connect local height energy to inverse-square gravity

At initial radius ratio 1, compare outward increments 0.1,0.5 and 1 body radius. Compute exact and local-constant-field energy changes and their discrepancy. Repeat from initial radius ratio 3 and explain why the same absolute increment is a smaller relative change there.

Derive elastic energy from a force-area construction

Compare compressions 0.10,0.20 and 0.40 m at fixed spring constant. Record force, stored energy and release speed. Then double stiffness while holding compression fixed. Explain why speed scales with the square root of stiffness rather than stiffness itself.

Read turning points and force directions from potential energy

Compare total energies 2,4 and 8 J. Locate turning points from the intersection condition before reading them. At E=2 J, test x=0 to produce a forbidden position; explain why the model withholds speed. Use graph slopes to identify force directions on both sides of the minimum.

Conserve total energy when mechanical energy decreases

Compare μ=0.2 and 0.5 for a requested 3 m, then request 5 m at μ=0.5. Reconstruct Kfinal+ΔEthermal and check it equals 36 J. Distinguish requested from actual travel, and explain why kinetic friction is not applied through a reversal after stopping.

Evaluate an energy transfer rate and a power constraint

Compare the same height over 1,2 and 4 s. Reconstruct useful and input energies separately from powers, then locate a schedule that fails the 250 W screen. Explain why satisfying this screen alone is not a validated real lifting design.

Unit 4 — Linear momentum7 lessons

Construct impulse and vector-momentum ledgers, distinguish elastic and inelastic interactions, and assess conservation evidence with bounded measurement error.

Add momenta and locate the system’s motion

Find two control pairs giving zero total momentum and compare their kinetic energies. Then choose equal velocities and verify the center has that same velocity. Explain why adding speeds instead of signed momenta would lose the system description.

Translate a force-time pulse into momentum change

Compare(8 N,0.5 s) with(4 N,1 s), then reverse the pulse sign. Calculate area, average force and final momentum before checking. Distinguish a zero final velocity from a zero force throughout the event. Sketch a momentum-time line rising from−2 to+2 kg m/s over2 s, then staying flat: the first segment has average net force+2 N and the flat segment zero, even though momentum remains+2 kg m/s.

Distinguish internal recoil from an external impulse

Hold internal impulse at 3 N s and compare external impulses−2,0 and+2 N s. Verify the sum of individual momentum changes. Then hold external impulse fixed and change internal impulse; identify which system quantity stays the same.

Use two conservation laws in an elastic collision

Compare equal masses with(2,3) and(3,2) kg. Reconstruct total momentum and kinetic energy from the individual final velocities. Check the 5 m/s relative separation and explain why individual energies can differ from their initial values.

Keep momentum while accounting for collision energy change

Find mass choices giving a small or zero final velocity. Reconstruct initial and final momenta and energies separately. Compare the same masses with the elastic model; identify which conserved quantity is common to both and which distinguishes them.

Construct separate component ledgers for a planar encounter

Compare inputs(3,4),(6,4) and(6,2) m/s. Sketch the component addition and predict direction changes before using output. Verify each component equation and distinguish a change in resultant direction from a change in total momentum magnitude.

Test conservation claims with bounded observation error

Compare the three supplied packets at the smallest and largest error bounds. Compute momentum and energy differences before reading the classifications. Identify one resolved kinetic decrease and one unresolved change. Explain why a compatible zero does not establish exact conservation from measurements.

Unit 5 — Torque and rotational dynamics9 lessons

Connect angular representations, extended force diagrams and axis-specific inertia to equilibrium, rotational acceleration and coupled-motion inference.

Read angular histories through a reversal

Compare α=−1 and α=0 over 4 s. Sketch angular velocity before checking the plot, mark the reversal if present, and calculate signed and absolute areas. Then choose α=−2 over 5 s and explain why final orientation alone is insufficient.

Connect a shared rotation to different point motions

Hold radius at 0.4 m and compare ω=2 with ω=4 rad/s. Draw the two perpendicular acceleration components at the rightmost point and compare their magnitudes. Then halve radius while retaining the angular quantities; distinguish an angular comparison from a linear one.

Locate the force before calculating its torque

Compare 0°, 30°, 90° and 150° at r=0.4 m. Sketch the force at the application point, extend its line of action and mark the perpendicular lever arm. Verify one calculation using Fℓ and another using rF sinφ.

Separate force balance from torque balance

Find three pairs that give zero net torque. Then hold the right force fixed and change only the left force. Draw all four forces, including weight and pivot reaction, and explain how net force stays zero while angular acceleration changes.

Build rotational inertia from five planar particles

Compare (a,b)=(0.2,0.2) with (0.4,0.4), then with (0.4,0.2). Make a five-row mass-coordinate table and calculate every contribution before checking. Explain why only the first comparison gives an exact factor of four.

Move the axis without moving the mass distribution

For mass 3 kg, compare offsets 0, 0.5, 1 and 2 m. Plot inertia against d² on paper using the ledger, identify the intercept and slope, and distinguish scaling the shift term from scaling the full sum.

Use two equilibrium conditions for an extended load

With W=80 N compare x=1, 2 and 3 m. Draw all forces at their true locations. Compute both reactions and check net torque about both supports. Then change the load while keeping its location fixed and separate the beam-weight contribution from the added-load contribution.

Infer angular change from net torque and inertia

Compare net torques 0 and +4 N m with inertia 2 kg m². Sketch angular velocity first, identify the moment of reversal, and compare signed graph area. Next double inertia at the same torque and predict how the reversal time changes.

Infer rotational inertia from a coupled motion model

Use at least three hanging masses while holding inertia fixed. Predict acceleration and tension, verify both Newton-law equations, and recover inertia from each synthetic acceleration. Then explain how a fixed opposing axle torque would alter the equation to a=(mg−τf/R)/(m+I/R²), and why treating it as zero could create mass-dependent inferred inertias.

Unit 6 — Energy and momentum of rotating systems8 lessons

Distinguish rotational energy and angular-momentum transfer, test rolling constraints and explain circular, elliptical and escape energy conditions.

Read rotational work from an angle-dependent torque

Compare start/end torques (4,−2), (2,−2) and (−4,−4). Compute each signed area and energy change. Sketch the cumulative work, identify where it reaches an extreme, and check that kinetic energy never reaches zero before the endpoint.

Recognize angular momentum in straight-line motion

Compare offsets +1, 0 and −1 m at speed 3 m/s. Draw the actual horizontal paths separately from the angular-momentum plot. Explain the unchanged linear momentum, changing reference-dependent angular momentum and zero torque in each case.

Connect torque-time evidence to angular-momentum change

Compare pulses (4 N m,1 s) and (2 N m,2 s), then reverse their signs. Reconstruct final angular momentum before checking. Sketch a separate L-time line rising from −2 to +2 over 2 s and then flat: its first average torque is +2 N m and its later torque is zero.

Test the energy and friction conditions for rolling

Compare all three supplied shape factors at h=0.6 m. Verify energy subtotals and derive the friction requirement for each. For a separate assigned surface μs=0.15, decide which no-slip predictions are feasible rather than applying every displayed speed unconditionally.

Identify the direction of friction from contact motion

Hold clockwise spin at 10 rad/s and compare center speeds 1, 2 and 3 m/s. Draw the center and rim contributions at contact, identify overspin/no-slip/underspin and predict the qualitative changes to translation and spin. Do not infer a transition time from this instantaneous snapshot.

Relate orbit shape, conserved quantities and escape energy

At r=20 m compare speed ratios 0.75, 1 and 1.5 relative to circular speed. Identify the circular case and the sign of specific total energy. Then compare circular orbits at 10 and 40 m and derive speed, energy and angular-momentum ratios before checking the ledger.

Unit 7 — Oscillations7 lessons

Derive linear restoring models, coordinate phase and energy, infer periods with bounded evidence and separate capture from later oscillation.

Locate equilibrium and test the restoring-force law

Compare x=0.1 and 0.2 m first with b=0, then b=100. Calculate F/x away from zero. Save contrasting captures and distinguish linearity from restoring direction; predict the force at negative displacement before checking.

Derive spring period and distinguish frequency measures

Choose two masses at one stiffness; predict the period ratio before capture. Then change stiffness to keep m/k fixed. Record T, f and ω separately, including their units. Explain which amplitude claim follows from the model rather than a measured spring.

Derive the pendulum approximation and test its boundary

Compare lengths 0.5 and 2 m at one amplitude, then compare 5° and 30° at fixed length. Explain why the displayed approximate period stays unchanged in the second comparison even though the approximation diagnostic worsens.

Coordinate displacement, velocity and acceleration phases

Capture phase fractions 0, 0.25, 0.5 and 0.75 for A=0.2 m. Predict signs before reading the ledger. Sketch separate labeled x–t, v–t and a–t graphs, and explain the slope relationships rather than copying a single curve into all three.

Use energy to reconstruct speed and turning points

Compare position fractions 0, 0.5 and 1 for one amplitude; reconstruct the total from each pair of energy entries. Then double amplitude while keeping the same position fraction and predict the energy and speed factors before capture.

Carry timing bounds into an inferred spring constant

At assigned timing error +0.1 s, compare N=1,5 and10. Save inferred periods and stiffness bounds. Check whether the true20 N/m is compatible, and explain which uncertainty sources the recipe deliberately excludes.

Change system boundaries between capture and oscillation

Compare center and endpoint capture for the same added mass. Write momentum and energy ledgers for the brief event, then a separate energy ledger for the later oscillation. Change added mass and predict whether amplitude and period both change in each case.

Unit 8 — Fluids9 lessons

Connect microscopic fluid properties to density, pressure forces, buoyancy and ideal-flow conservation; test feasibility and infer parameters from bounded observations.

Infer density without confusing sample mass and tare

Compare tare 0 and0.10 kg at density1000, then density500 and1500 at fixed tare. Retain two sample points and the zero-volume point; derive the slope and intercept rather than reading one ratio. Explain why the dashed sample-only curve differs from the observed curve.

Distinguish scalar pressure from a normal force

Compare the supplied force and area separately, then double both within the available settings. Write one-face pressure and explain what additional opposite-face pressure is needed for net force. Sketch normal-force directions on two differently oriented walls at equal pressure.

Build pressure from equilibrium and a stated reference

Compare oil thickness0.1 and0.5 m at water depth0.5 m. Then vary only water depth. Reconstruct both increments and the slope on each part of the graph. Explain why the graph uses absolute pressure and why its zero-depth value is not zero.

Derive buoyancy and distinguish support from free motion

Hold mass3 kg and compare top depths0.1 and0.5 m, then compare masses1 and5 kg at fixed depth. Distinguish opposing pressure forces, their resultant, signed holding force and the ideal released acceleration. Explain which cases require downward rather than overhead restraint.

Conserve mass flow without inventing a branch split

At inlet speed1, compare branch fractions0.25,0.5 and0.75. Reconstruct eachQ from its own area and speed, then sum. Change inlet speed while fixing the split and predict all flow ratios before capture. State why the fraction requires independent information.

Infer fluid head from an ideal jet without mixing two heights

Vary head at fixed outlet height, then vary outlet height at fixed head. Reconstruct speed and flight time separately before calculating range. Use the assigned range error to bound inferred head; identify a loss mechanism that would bias inference even if repeated ranges were precise.

Full-course synthesis and evidence audit2 lessons

Select laws by system and interval, test physical feasibility, integrate representations and distinguish independent evidence from agreement caused by shared assumptions.

Audit a multi-stage mechanism by changing system and law

Compare the passing case (x=0.30,μ=0.10), a stopped case (0.10,0.20), and threshold (0.10,0.125). Retain a stage diagram and separate energy/momentum ledgers. Change launch compression and predict the feasibility boundary before capture. Explain why no downstream speed is displayed for a failed path.

Test whether agreement between methods is independent evidence

Compare c=1 and1.05 with lagzero, then introduce lag0.05 at fixedc. Save both method estimates and the multiheight fall packet. Propose a genuinely independent calibration and predict how its evidence would differ under clock-scale versus fall-lag explanations. Specify how length error could confound the comparison.

Investigation portfolio

Keep predictions before comparison, complete raw records and units, explain competing models and test a changed case. Supplied and simulated data are labeled in each lesson. A saved notebook is not proof of experimental technique or correct reasoning.

System-boundary and component investigation

Evidence to retain: Keep separate diagrams for each recipient, compare whole-system and single-object statements, and predict which quantities change when mass or force components change.

Boundary: Ideal point-object models; horizontal component diagrams omit balanced vertical interactions only where explicitly stated.

Infer a parameter and challenge a constraint

Evidence to retain: Infer mass from a slope with a nonzero sensor offset; test friction regime, spring calibration and circular-force feasibility; use a mass-swap intervention to distinguish shared acceleration from internal tension.

Boundary: Supplied synthetic data and bounded models, not instrument calibration evidence or a validated real connector design.

Work and potential-energy construction

Evidence to retain: Retain paired settings and reconstruct force-position areas, frame-dependent kinetic energies, exact versus local gravitational changes and spring-energy scaling.

Boundary: Original bounded models, not measured energy transfers; each approximation and zero choice is explicit.

Energy-state and schedule rejection

Evidence to retain: Identify inaccessible positions, premature stopping and infeasible power schedules; explain a changed-case prediction before revealing results.

Boundary: A rejected state is not reported as an achieved trajectory; real thermal, material and practical constraints are not validated.

Collision classification and error audit

Evidence to retain: Reconstruct before/after momentum and kinetic energy, set up planar component equations, and distinguish a resolved difference from compatibility with zero under explicit bounds.

Boundary: Synthetic packets and exact masses do not establish actual collision measurements, calibration or secure independent assessment.

Geometry and equilibrium audit

Evidence to retain: Retain actual force locations, compare two pivots, reconstruct five-particle inertia, and test a reaction-force prediction under a changed load position.

Boundary: Original virtual geometries; no structural rating, load-bearing construction or physical suspended-weight activity.

Coupled-motion parameter inference

Evidence to retain: Predict before controls; keep raw synthetic accelerations for several masses, derive both Newton-law equations and the no-slip constraint, propagate an assigned interval, and challenge friction/radius assumptions.

Boundary: Supplied/model-generated observations do not establish instrument calibration, independently measured inertia, laboratory time or supervised practical proficiency.

Angular transfer and system-boundary evidence

Evidence to retain: Contrast torque-angle and torque-time areas, preserve the same axis, compare initial/final energy and angular momentum under redistribution or joining, and evaluate a bounded residual.

Boundary: Virtual pulses and endpoint states only; no high-speed rotor, clutch, human spinning or stored-energy apparatus.

Constraint feasibility and orbital invariants

Evidence to retain: Check the static-friction requirement before accepting a rolling prediction; diagnose slipping qualitatively; reconstruct circular and elliptical conservation ledgers and an escape threshold.

Boundary: No quantitative slipping-time requirement, rolling-resistance model, physical incline experiment or launch activity. Synthetic outputs are not independent measurements.

Restoring-law and period discrimination

Evidence to retain: Compare force-to-displacement ratios, spring mass/stiffness scaling and pendulum approximation diagnostics; predict phase signs and retain contrasting settings.

Boundary: Virtual idealized systems only; no spring loading, overhead suspension or physical pendulum construction. A restoring-force discrepancy is not an exact pendulum period correction.

Timing inference and stage-dependent conservation

Evidence to retain: Carry total-time bounds into period and stiffness; evaluate a T² fit and residuals; compare center and endpoint capture with separate momentum and energy ledgers.

Boundary: Assigned timing errors and idealized attachment, not observed measurements or a secure independent assessment. No physical capture apparatus.

Density, pressure and reference inference

Evidence to retain: Infer density and tare from a mass-volume graph; distinguish force components and pressure references; predict layered pressure and hydraulic displacement/work.

Boundary: Synthetic readings and ideal static systems, not immersion of unknown materials, pressurization or load-bearing equipment.

Flow and inverse-evidence audit

Evidence to retain: Close branch volume/mass flows, combine continuity with three-term energy conservation and infer head from range with a stated error bound. Identify an observation that could falsify an ideal assumption.

Boundary: Steady full-pipe idealization and supplied jet records only; no actual jet construction, machinery operation or independently measured flow.

Stage feasibility and common-error challenge

Evidence to retain: Retain passing, stopped and threshold cases; account for every energy transfer and choose momentum intervals. Compare two gravity methods under shared and method-specific bias, then design an independent test that discriminates alternatives.

Boundary: Original supplied-data models only. No physical spring launch, collision, drop or suspension; practical execution needs qualified local supervision and a separately reviewed safe design.

Rest-release parameter investigation

Evidence to retain: Choose sampling interval, retain raw selected coordinates, fit acceleration, state bounded error, test held-out evidence and propose an independent calibration check.

Boundary: Synthetic supplied data; does not establish laboratory time, instrument competence or independent practical review.

Mixed assessment and cumulative project

Open the retained response and project workspaces. Practice, saved work and independently reviewed proficiency remain separate.

Mixed assessment and retained reasoning

These 42 course-specific public tasks are practice, not a secure examination. Each retains up to three immutable written responses, known feedback exposure before each response, and human rubric critiques. Drafts remain editable. No text-length check or self-reported review certifies correctness, independence, laboratory skill or mastery.

1. Two-dimensional systems and circular constraints

Find the center of mass for 1 kg at (0,0), 2 kg at (6,0) and 3 kg at (0,4). Separately derive the frictionless bank angle condition for radius 20 m and speed 10 m/s with g=10 m/s². Compare periods for circular orbits whose radii differ by a factor of 4 around the same dominant mass.

Course-specific review criteria

  • Compute both mass-weighted coordinates and total mass.
  • Resolve normal force into vertical and inward components before taking a ratio.
  • Combine gravitational and circular-motion equations rather than holding orbital speed fixed.

Include calculations with units, source or dataset provenance, assumptions, competing explanations and limitations as relevant. The draft is saved but is not a locked response until submitted.

0/3 responses retained. No recorded feedback exposure for this task version. Earlier versions may already be familiar. Public inspectability still prevents certification of unfamiliarity.

2. Mixed forces case: angled pull and friction

A 4 kg block on a horizontal track is pulled by 20 N at 30° above horizontal. Use g=10 m/s², μs=0.5 and μk=0.3. The block starts at rest. Determine normal force, whether rest is possible, and initial horizontal acceleration if it slides. Name the third-law partner of the normal force.

Course-specific review criteria

  • Use vertical balance to obtain N rather than assuming N=mg.
  • Compare horizontal pull with the static limit before choosing a friction rule.
  • Use kinetic friction only after the rest test fails.
  • Reverse agent and recipient for the third-law partner.

Include calculations with units, source or dataset provenance, assumptions, competing explanations and limitations as relevant. The draft is saved but is not a locked response until submitted.

0/3 responses retained. No recorded feedback exposure for this task version. Earlier versions may already be familiar. Public inspectability still prevents certification of unfamiliarity.

3. Changed coupled-system case

The leading cart has mass 2 kg and trailing cart 3 kg. A 20 N pull acts on the leader and a constant 4 N opposing horizontal force acts on the trailer. Derive acceleration and string tension. Then remove the opposing force and swap the masses: identify which quantities change.

Course-specific review criteria

  • Write an equation for each cart and define signs.
  • Treat the opposing interaction as external to the two-cart system.
  • Cancel internal tension only when adding system equations.
  • Check the answer in both individual equations.

Include calculations with units, source or dataset provenance, assumptions, competing explanations and limitations as relevant. The draft is saved but is not a locked response until submitted.

0/3 responses retained. No recorded feedback exposure for this task version. Earlier versions may already be familiar. Public inspectability still prevents certification of unfamiliarity.

4. Gravity, springs and circular constraints

A 2 kg object is moved from a spherical body’s surface to center distance 2R; surface g=10 N/kg. Separately, an ideal spring with k=50 N/m is compressed by 0.10 m. Finally a 2 kg object requires a horizontal circle of radius 1 m at 4 m/s with a connector limit 20 N. Find weight, signed spring force for negative compression, and circle feasibility. Explain why the same force formula cannot be used for all three.

Course-specific review criteria

  • Use center distance rather than altitude in inverse-square gravity.
  • Retain the restoring sign in Hooke’s law.
  • Compare required inward force with the constraint before accepting circular motion.

Include calculations with units, source or dataset provenance, assumptions, competing explanations and limitations as relevant. The draft is saved but is not a locked response until submitted.

0/3 responses retained. No recorded feedback exposure for this task version. Earlier versions may already be familiar. Public inspectability still prevents certification of unfamiliarity.

5. Mixed work and kinetic-energy case

A 2 kg object begins with 20 J kinetic energy. A net horizontal force varies linearly from 6 N to −2 N over a 4 m positive displacement. Find net work and final speed. Explain why adding area magnitudes or using force-time area would answer different questions.

Course-specific review criteria

  • Use signed trapezoidal area.
  • Add net work to initial kinetic energy.
  • Convert energy to speed with mass and a square root.

Include calculations with units, source or dataset provenance, assumptions, competing explanations and limitations as relevant. The draft is saved but is not a locked response until submitted.

0/3 responses retained. No recorded feedback exposure for this task version. Earlier versions may already be familiar. Public inspectability still prevents certification of unfamiliarity.

6. Potential energy and accessible positions

Three equal masses occupy an equilateral triangle of side r. Write their total gravitational potential energy using zero at infinite separation. Separately, a 2 kg particle has E=4 J in U=2|x−2| J: find turning points, speed at x=1, and force direction on each side of x=2.

Course-specific review criteria

  • Count each distinct pair once.
  • Use E−U rather than equating potential with kinetic energy.
  • Infer force direction from negative graph slope.

Include calculations with units, source or dataset provenance, assumptions, competing explanations and limitations as relevant. The draft is saved but is not a locked response until submitted.

0/3 responses retained. No recorded feedback exposure for this task version. Earlier versions may already be familiar. Public inspectability still prevents certification of unfamiliarity.

7. Spring release with a dissipative track

A 1 kg cart starts at rest against an ideal spring k=100 N/m compressed 0.20 m. After release to equilibrium it enters a horizontal rough track with constant friction 0.5 N. Find entry speed and stopping distance. Give separate consistent ledgers for cart alone and cart+spring+surface.

Course-specific review criteria

  • Derive stored energy from the triangular force-area construction.
  • Do not continue past zero kinetic energy.
  • Do not count internal friction conversion twice.

Include calculations with units, source or dataset provenance, assumptions, competing explanations and limitations as relevant. The draft is saved but is not a locked response until submitted.

0/3 responses retained. No recorded feedback exposure for this task version. Earlier versions may already be familiar. Public inspectability still prevents certification of unfamiliarity.

8. Rate and efficiency design screen

Lift 10 kg through 4 m in 2 s at constant speed with g=10 m/s² and 80% efficiency. Compute useful work, input energy and required input power. A second schedule takes 1 s: which quantities change, and does either exceed a 250 W input limit?

Course-specific review criteria

  • Separate energy from power.
  • Divide by efficiency for required input.
  • Treat an excessive requirement as rejected rather than achieved.

Include calculations with units, source or dataset provenance, assumptions, competing explanations and limitations as relevant. The draft is saved but is not a locked response until submitted.

0/3 responses retained. No recorded feedback exposure for this task version. Earlier versions may already be familiar. Public inspectability still prevents certification of unfamiliarity.

9. Stopping versus rebound pulses

A virtual 0.5 kg object moves at +4 m/s before contact. Compare stopping with rebound at −4 m/s. Find impulses. If the rebound pulse is triangular and lasts 0.20 s, find its signed average and peak force. What changes if duration doubles with the same impulse and pulse shape?

Course-specific review criteria

  • Subtract signed momenta.
  • Distinguish average from peak force.
  • Hold impulse and pulse shape explicit when changing duration.

Include calculations with units, source or dataset provenance, assumptions, competing explanations and limitations as relevant. The draft is saved but is not a locked response until submitted.

0/3 responses retained. No recorded feedback exposure for this task version. Earlier versions may already be familiar. Public inspectability still prevents certification of unfamiliarity.

10. Compare elastic and sticking outcomes

Masses 2 and 3 kg approach at +4 and −1 m/s with negligible external impulse. Compare their elastic final velocities with the shared sticking velocity; calculate kinetic-energy change for each model.

Course-specific review criteria

  • Preserve signed total momentum.
  • Apply kinetic-energy conservation only to the elastic case.
  • Account for the sticking energy decrease without calling it destruction.

Include calculations with units, source or dataset provenance, assumptions, competing explanations and limitations as relevant. The draft is saved but is not a locked response until submitted.

0/3 responses retained. No recorded feedback exposure for this task version. Earlier versions may already be familiar. Public inspectability still prevents certification of unfamiliarity.

11. Vector ledger and measurement boundary

A 2 kg object at 3 m/s east sticks to a 3 kg object at 4 m/s north. Set up the component equations and infer shared components. Separately, four velocity observations of two exact 1 kg objects each have error at most 0.02 m/s; observed total momentum change is 0.06 kg m/s. Is zero change compatible, and is it proven?

Course-specific review criteria

  • Conserve components separately rather than adding magnitudes.
  • Use total mass for each shared velocity component.
  • Sum worst-case error contributions and distinguish compatibility from proof.

Include calculations with units, source or dataset provenance, assumptions, competing explanations and limitations as relevant. The draft is saved but is not a locked response until submitted.

0/3 responses retained. No recorded feedback exposure for this task version. Earlier versions may already be familiar. Public inspectability still prevents certification of unfamiliarity.

12. A virtual catch-and-rise: different laws in different stages

In a supplied virtual case, a 0.2 kg object moving at 10 m/s is caught by a stationary 1.8 kg carrier. They stick with negligible horizontal external impulse during the brief catch, then rise without further mechanical-energy loss. Use g=10 m/s². Find immediate shared speed and rise height; explain why one energy-conservation equation cannot be applied across the entire event.

Course-specific review criteria

  • Use momentum during the inelastic catch.
  • Use mechanical energy only for the subsequent ideal rise.
  • Identify the kinetic-energy decrease during capture.

Include calculations with units, source or dataset provenance, assumptions, competing explanations and limitations as relevant. The draft is saved but is not a locked response until submitted.

0/3 responses retained. No recorded feedback exposure for this task version. Earlier versions may already be familiar. Public inspectability still prevents certification of unfamiliarity.

13. A reversing rotor and two marked points

A rigid rotor starts at +3 rad/s with constant α=−1 rad/s² for 6 s. Find angular displacement, angular travel and final angular velocity. At t=2 s, compare speeds and inward accelerations of points at radii 0.2 and 0.4 m. Give their tangential acceleration magnitudes.

Course-specific review criteria

  • Split angular travel at the reversal.
  • Use instantaneous angular velocity for centripetal acceleration.
  • Separate angular quantities from radius-dependent linear quantities.

Include calculations with units, source or dataset provenance, assumptions, competing explanations and limitations as relevant. The draft is saved but is not a locked response until submitted.

0/3 responses retained. No recorded feedback exposure for this task version. Earlier versions may already be familiar. Public inspectability still prevents certification of unfamiliarity.

14. A reaction calculation checked about two pivots

A uniform 4 m beam weighs 40 N. A 60 N downward point load is at x=1 m from the left support. Find both upward support reactions and check torque balance about each support. Explain why force balance alone is insufficient and why this is not a construction safety rating.

Course-specific review criteria

  • Represent weight at the midpoint and load at its specified position.
  • Apply both equilibrium conditions.
  • Retain contact and rigid-body model limits.

Include calculations with units, source or dataset provenance, assumptions, competing explanations and limitations as relevant. The draft is saved but is not a locked response until submitted.

0/3 responses retained. No recorded feedback exposure for this task version. Earlier versions may already be familiar. Public inspectability still prevents certification of unfamiliarity.

15. Five particles and a shifted axis

Four 1 kg particles lie at (±0.3,±0.4) m and a fifth 2 kg particle at the origin. Find inertia about the perpendicular center axis, then about a parallel axis 0.5 m away. A net +5 N m torque acts about the shifted fixed axis; find angular acceleration. Explain why the 2 kg particle has zero contribution about the first axis but not the second.

Course-specific review criteria

  • Use squared perpendicular distances for all five particles.
  • Apply the parallel-axis theorem from the center of mass.
  • Match the torque and inertia axes.

Include calculations with units, source or dataset provenance, assumptions, competing explanations and limitations as relevant. The draft is saved but is not a locked response until submitted.

0/3 responses retained. No recorded feedback exposure for this task version. Earlier versions may already be familiar. Public inspectability still prevents certification of unfamiliarity.

16. Model-dependent pulley inference

A supplied virtual pulley case uses m=1 kg, R=0.10 m and g=10 m/s². Acceleration is reported as 3.2–3.4 m/s² with other quantities exact. Infer the inertia interval under no slip and negligible bearing friction. Then explain how a positive opposing bearing torque biases an inference that omits it, and propose a discriminating comparison.

Course-specific review criteria

  • Derive translation, rotation and no-slip equations separately.
  • Reverse interval endpoints for the decreasing inference function.
  • Explain confounding and an additional test, not just recompute a nominal number.

Include calculations with units, source or dataset provenance, assumptions, competing explanations and limitations as relevant. The draft is saved but is not a locked response until submitted.

0/3 responses retained. No recorded feedback exposure for this task version. Earlier versions may already be familiar. Public inspectability still prevents certification of unfamiliarity.

17. Two areas with different consequences

A fixed-axis rotor has I=2 kg m² and begins with rotational energy 20 J. Its net torque falls linearly from +4 to −2 N m across +2 rad. Find work and final angular speed, assuming no reversal. Separately, a triangular +4 N m torque pulse lasts 1 s. Find its angular impulse and explain why the first graph does not give that impulse.

Course-specific review criteria

  • Label the independent variable and area unit.
  • Apply net work to energy and torque-time area to angular momentum.
  • Do not invent elapsed time from an angle axis.

Include calculations with units, source or dataset provenance, assumptions, competing explanations and limitations as relevant. The draft is saved but is not a locked response until submitted.

0/3 responses retained. No recorded feedback exposure for this task version. Earlier versions may already be familiar. Public inspectability still prevents certification of unfamiliarity.

18. Joining and contraction conserve different subtotals

Two coaxial rotors have inertias 2 and 1 kg m² and initial angular velocities +4 and −2 rad/s. They join through internal friction with negligible external axle torque. Find shared final speed, total angular momentum and kinetic-energy change. Then a separate isolated system with L=6 kg m²/s contracts from I=4 to I=2 kg m²; compare its energy change.

Course-specific review criteria

  • Add signed momenta about one axis.
  • Use the combined system for internal torque cancellation.
  • Distinguish dissipative joining from energy-converting contraction.

Include calculations with units, source or dataset provenance, assumptions, competing explanations and limitations as relevant. The draft is saved but is not a locked response until submitted.

0/3 responses retained. No recorded feedback exposure for this task version. Earlier versions may already be familiar. Public inspectability still prevents certification of unfamiliarity.

19. A no-slip prediction that must be rejected

A uniform disk with I=½mR² is released on a 30° incline. Use g=10 m/s². Derive the minimum static coefficient needed for no-slip rolling and test an assigned μs=0.15. Separately, a disk moving right has contact slipping left due to overspin: predict friction direction and qualitative changes in translation, clockwise spin and total mechanical energy.

Course-specific review criteria

  • Use force and torque equations with the no-slip constraint.
  • Compare required friction with its bound before accepting the model.
  • Distinguish contact slip from center motion.

Include calculations with units, source or dataset provenance, assumptions, competing explanations and limitations as relevant. The draft is saved but is not a locked response until submitted.

0/3 responses retained. No recorded feedback exposure for this task version. Earlier versions may already be familiar. Public inspectability still prevents certification of unfamiliarity.

20. An elliptical conservation cross-check

For an ideal central parameter GM=100 m³/s², a satellite has closest and farthest radii 10 and 30 m. At those points velocity is perpendicular to radius. Use angular momentum and energy conservation to check vp=√15 m/s and va=√15/3 m/s. Find specific total energy and compare escape speed at 10 m.

Course-specific review criteria

  • Use transverse velocity at the apsides.
  • Keep U negative with the infinity reference.
  • Do not apply the circular kinetic-energy formula to an ellipse.

Include calculations with units, source or dataset provenance, assumptions, competing explanations and limitations as relevant. The draft is saved but is not a locked response until submitted.

0/3 responses retained. No recorded feedback exposure for this task version. Earlier versions may already be familiar. Public inspectability still prevents certification of unfamiliarity.

21. Conservation evidence is not exact proof

Before and after angular momenta are independently bounded within 0.04 kg m²/s each, and the observed difference is +0.06 kg m²/s. Is zero change compatible? A separate straight-line 2 kg particle moves right at 3 m/s on y=1 m: find signed angular momentum about the origin, counterclockwise tendency positive, and explain why it stays constant.

Course-specific review criteria

  • Add worst-case error magnitudes without inventing a confidence level.
  • Name external torque and measurement assumptions.
  • Retain reference-dependent perpendicular offset.

Include calculations with units, source or dataset provenance, assumptions, competing explanations and limitations as relevant. The draft is saved but is not a locked response until submitted.

0/3 responses retained. No recorded feedback exposure for this task version. Earlier versions may already be familiar. Public inspectability still prevents certification of unfamiliarity.

22. Gravity shifts equilibrium, not linear stiffness

A vertical ideal spring has k=40 N/m and supports m=2 kg; use g=10 m/s². Find equilibrium extension. At 0.10 m below that equilibrium find net force and acceleration. Compare the period with the same mass and spring oscillating horizontally without friction.

Course-specific review criteria

  • Distinguish extension from equilibrium displacement.
  • Include weight before shifting coordinates.
  • Use the same k/m for the ideal period.

Include calculations with units, source or dataset provenance, assumptions, competing explanations and limitations as relevant. The draft is saved but is not a locked response until submitted.

0/3 responses retained. No recorded feedback exposure for this task version. Earlier versions may already be familiar. Public inspectability still prevents certification of unfamiliarity.

23. One position, two possible directions

An ideal oscillator has m=2 kg,k=20 N/m,A=0.20 m. At x=+0.10 m find acceleration, potential energy, kinetic energy and speed. Can velocity direction be deduced? Predict all quantities at the negative endpoint.

Course-specific review criteria

  • Use displacement sign for acceleration.
  • Keep energy scalar and nonnegative.
  • Do not infer phase direction from position alone.

Include calculations with units, source or dataset provenance, assumptions, competing explanations and limitations as relevant. The draft is saved but is not a locked response until submitted.

0/3 responses retained. No recorded feedback exposure for this task version. Earlier versions may already be familiar. Public inspectability still prevents certification of unfamiliarity.

24. Approximation versus actual period

Two ideal small-angle pendulums are at the same gravity: lengths0.5 and2 m, with different bob masses. Compare approximate periods. Then the longer pendulum amplitude rises from5° to30°. Explain why an unchanged displayed small-angle prediction is not proof that actual period stays constant, and why the endpoint sinθ/θ discrepancy is not a period error.

Course-specific review criteria

  • Use length ratio and mass cancellation.
  • Name small-angle and point-bob assumptions.
  • Separate a force-term diagnostic from an integrated timing result.

Include calculations with units, source or dataset provenance, assumptions, competing explanations and limitations as relevant. The draft is saved but is not a locked response until submitted.

0/3 responses retained. No recorded feedback exposure for this task version. Earlier versions may already be familiar. Public inspectability still prevents certification of unfamiliarity.

25. A bounded timing result and an imperfect fit

Five complete cycles take7.00±0.20 s, with exact mass1 kg. Find period bounds and stiffness bounds under the ideal spring model. Separately, a T²-versus-m fit is T²=2m+0.20 in SI units. Infer stiffness from slope and explain what the intercept does and does not establish.

Course-specific review criteria

  • Divide total-time bounds by cycle count.
  • Reverse endpoints for inverse-square stiffness.
  • Treat a nonzero intercept as a model diagnostic, not unique causal proof.

Include calculations with units, source or dataset provenance, assumptions, competing explanations and limitations as relevant. The draft is saved but is not a locked response until submitted.

0/3 responses retained. No recorded feedback exposure for this task version. Earlier versions may already be familiar. Public inspectability still prevents certification of unfamiliarity.

26. Two captures, one final period

A1 kg horizontal oscillator with k=20 N/m and amplitude0.20 m captures1 kg initially at rest horizontally. Compare capture at equilibrium with capture at the positive endpoint. Find new amplitude, period and horizontal mechanical energy in each case; identify the short-impulse approximation.

Course-specific review criteria

  • Apply momentum only during the short attachment.
  • Account for inelastic energy conversion at center capture.
  • Use post-event energy for later oscillation.

Include calculations with units, source or dataset provenance, assumptions, competing explanations and limitations as relevant. The draft is saved but is not a locked response until submitted.

0/3 responses retained. No recorded feedback exposure for this task version. Earlier versions may already be familiar. Public inspectability still prevents certification of unfamiliarity.

27. A slope with a tare and a bounded mass difference

Observed masses are 0.30 and 0.70 kg at exact volumes 0.0002 and 0.0006 m³. Each mass has an assigned error bound ±0.01 kg. Infer density, intercept and worst-case density interval. Explain why one raw mass/volume ratio is not the same result.

Course-specific review criteria

  • Use differences to remove a constant tare.
  • Add worst-case mass-error magnitudes.
  • Separate sample density from a raw ratio containing an offset.

Include calculations with units, source or dataset provenance, assumptions, competing explanations and limitations as relevant. The draft is saved but is not a locked response until submitted.

0/3 responses retained. No recorded feedback exposure for this task version. Earlier versions may already be familiar. Public inspectability still prevents certification of unfamiliarity.

28. Layered pressure and a plate resultant

Oil density800 kg/m³ occupies0.30 m above water. A point is0.50 m below the interface. Use g=10 and surface pressure100000 Pa. Find its absolute and gauge pressures. A small horizontal plate at that point has area0.002 m² and opposite-face pressure100000 Pa; assuming uniform pressure on each face, find net force magnitude.

Course-specific review criteria

  • Sum separate density-depth increments.
  • Name the pressure reference.
  • Use pressure difference for net load.

Include calculations with units, source or dataset provenance, assumptions, competing explanations and limitations as relevant. The draft is saved but is not a locked response until submitted.

0/3 responses retained. No recorded feedback exposure for this task version. Earlier versions may already be familiar. Public inspectability still prevents certification of unfamiliarity.

29. Hydraulic gain with a height correction

Small and large piston areas are0.001 and0.004 m². Applied force above ambient is60 N. At equal heights find output force and displacement for input travel0.10 m, then compare work. Separately, if the output piston is1 m higher in fluidρ1000 withg10, find the pressure-corrected output force at a static instant.

Course-specific review criteria

  • Combine pressure and displaced-volume constraints.
  • Do not create work by force amplification.
  • Include hydrostatic pressure change when heights differ.

Include calculations with units, source or dataset provenance, assumptions, competing explanations and limitations as relevant. The draft is saved but is not a locked response until submitted.

0/3 responses retained. No recorded feedback exposure for this task version. Earlier versions may already be familiar. Public inspectability still prevents certification of unfamiliarity.

30. Supported immersion versus impossible floating

A fully immersed object has mass4 kg and volume0.003 m³ in fluidρ800 withg10. Find buoyancy and upward holding force. Separately, a sealed box of total mass12 kg has maximum displaced volume0.010 m³ in waterρ1000. Evaluate a claimed floating equilibrium and identify what remains unknown even if vertical balance were feasible.

Course-specific review criteria

  • Use fluid density and displaced volume.
  • Distinguish holding force from buoyancy.
  • Reject impossible displacement rather than clipping.

Include calculations with units, source or dataset provenance, assumptions, competing explanations and limitations as relevant. The draft is saved but is not a locked response until submitted.

0/3 responses retained. No recorded feedback exposure for this task version. Earlier versions may already be familiar. Public inspectability still prevents certification of unfamiliarity.

31. Continuity does not supply every boundary condition

An inlet area0.004 m² carries water at1 m/s. A supplied split sends25% to a0.001 m² branch and75% to a0.002 m² branch. Find both branch speeds. In a separate unbranched ideal pipe, area halves, inlet speed1 m/s, inlet pressure200000 Pa and outlet rises2 m; find outlet pressure forρ1000,g10.

Course-specific review criteria

  • Preserve the given branch fraction.
  • Use area, not radius, in continuity.
  • Apply energy only to the stated streamline and boundary.

Include calculations with units, source or dataset provenance, assumptions, competing explanations and limitations as relevant. The draft is saved but is not a locked response until submitted.

0/3 responses retained. No recorded feedback exposure for this task version. Earlier versions may already be familiar. Public inspectability still prevents certification of unfamiliarity.

32. An inferred head with conditional error bounds

A supplied horizontal-jet range is1.20±0.02 m and outlet height0.60 m is exact. Under a large-open-tank, negligible-drag model infer head and its interval. Identify two systematic effects that the range interval does not cover, and distinguish outlet height from head.

Course-specific review criteria

  • Combine Torricelli and projectile relations before inversion.
  • Evaluate squared range endpoints.
  • Name excluded model errors rather than treating precision as accuracy.

Include calculations with units, source or dataset provenance, assumptions, competing explanations and limitations as relevant. The draft is saved but is not a locked response until submitted.

0/3 responses retained. No recorded feedback exposure for this task version. Earlier versions may already be familiar. Public inspectability still prevents certification of unfamiliarity.

33. Motion graph, force model and frame

A 3 kg cart begins at x=2 m with v=4 m/s. Its net horizontal force is −6 N for3 s, with no controller stopping it at reversal. Find final position, displacement, distance and final momentum. An observer moves at+1 m/s: compare the cart’s displacement and acceleration in that frame.

Course-specific review criteria

  • Use constant acceleration only over its stated interval.
  • Split distance at velocity reversal.
  • Distinguish frame-dependent displacement from acceleration under constant-velocity transformation.

Include calculations with units, source or dataset provenance, assumptions, competing explanations and limitations as relevant. The draft is saved but is not a locked response until submitted.

0/3 responses retained. No recorded feedback exposure for this task version. Earlier versions may already be familiar. Public inspectability still prevents certification of unfamiliarity.

34. A successful path and a rejected path

Use the synthesis cart assumptions. First compression0.30 m and friction coefficient0.10: find arrival energy, shared capture speed and final compression. Then compression0.10 m with coefficient0.20: determine whether capture occurs and explain why a negative proposed kinetic energy is not a physical result.

Course-specific review criteria

  • Check reachability before downstream formulas.
  • Separate friction conversion from inelastic conversion.
  • Use post-capture rather than original energy for final compression.

Include calculations with units, source or dataset provenance, assumptions, competing explanations and limitations as relevant. The draft is saved but is not a locked response until submitted.

0/3 responses retained. No recorded feedback exposure for this task version. Earlier versions may already be familiar. Public inspectability still prevents certification of unfamiliarity.

35. A torque pulse versus a torque-angle process

A fixed-axis rotor has I=2 kg m² and initial angular velocity+1 rad/s. A triangular net torque pulse peaks at+6 N m over2 s. Find final angular momentum and angular velocity. Is its rotational-energy gain equal to the numerical torque-time area? Separately, infer work from a constant3 N m torque over2 rad.

Course-specific review criteria

  • Distinguish torque-time and torque-angle dimensions.
  • Retain initial angular momentum.
  • Check energy independently rather than relabeling impulse.

Include calculations with units, source or dataset provenance, assumptions, competing explanations and limitations as relevant. The draft is saved but is not a locked response until submitted.

0/3 responses retained. No recorded feedback exposure for this task version. Earlier versions may already be familiar. Public inspectability still prevents certification of unfamiliarity.

36. Which conservation shortcut is valid?

A uniform disk withβ=0.5 rolls from rest through vertical drop0.60 m on a30° stationary incline withg10. Derive its no-slip speed and test μs=0.15. Separately, a gravity-only satellite has GM=100,closest radius10 and speed√15 at that point; decide whether the local circular-speed equation applies and calculate specific total energy.

Course-specific review criteria

  • Check required friction before accepting a rolling solution.
  • Distinguish an ideal conditional result from a feasible trajectory.
  • Do not apply circular formulas to arbitrary bound orbits.

Include calculations with units, source or dataset provenance, assumptions, competing explanations and limitations as relevant. The draft is saved but is not a locked response until submitted.

0/3 responses retained. No recorded feedback exposure for this task version. Earlier versions may already be familiar. Public inspectability still prevents certification of unfamiliarity.

37. Phase, energy and a changed mass

An ideal horizontal oscillator has m=2 kg,k=20 N/m,A=0.20 m. Atx=−0.10 m find acceleration, kinetic energy and possible velocity signs. If another2 kg with zero horizontal velocity is captured at the positive endpoint instead, predict the new amplitude and period ratio.

Course-specific review criteria

  • Use signed displacement for acceleration.
  • Use energy to find speed magnitude, not direction.
  • Separate endpoint capture from center capture.

Include calculations with units, source or dataset provenance, assumptions, competing explanations and limitations as relevant. The draft is saved but is not a locked response until submitted.

0/3 responses retained. No recorded feedback exposure for this task version. Earlier versions may already be familiar. Public inspectability still prevents certification of unfamiliarity.

38. Displacement and pressure are not the same quantity

A sealed object has total mass6 kg and maximum external volume0.005 m³ in waterρ1000,g10. Can it float? If fully immersed, find buoyancy and the upward support needed. Explain whether moving the rigid object deeper in uniform water changes buoyancy.

Course-specific review criteria

  • Test required displacement against available volume.
  • Distinguish weight, buoyancy and support.
  • Use pressure difference rather than absolute pressure alone.

Include calculations with units, source or dataset provenance, assumptions, competing explanations and limitations as relevant. The draft is saved but is not a locked response until submitted.

0/3 responses retained. No recorded feedback exposure for this task version. Earlier versions may already be familiar. Public inspectability still prevents certification of unfamiliarity.

39. Continuity, energy and inverse projectile evidence

In an unbranched ideal pipe, inlet area0.004 m²,speed1 m/s,pressure200000 Pa; outlet area0.002 m² and elevation2 m higher. Useρ1000,g10 to find outlet speed/pressure. Separately a horizontal open-tank jet has range1.20±0.02 m at outlet height0.60 m. Infer head and interval without equating head with outlet height.

Course-specific review criteria

  • Use area continuity before Bernoulli.
  • Keep pressure-work, kinetic and gravitational terms.
  • Propagate a range bound only under stated ideal geometry.

Include calculations with units, source or dataset provenance, assumptions, competing explanations and limitations as relevant. The draft is saved but is not a locked response until submitted.

0/3 responses retained. No recorded feedback exposure for this task version. Earlier versions may already be familiar. Public inspectability still prevents certification of unfamiliarity.

40. Agreement with a shared calibration error

Two supplied gravity methods use the same clock with scale1.05 and no added method-specific lag. True gravity in the teaching generator is10 m/s². Calculate both estimates and propose an observation that can distinguish shared timing bias from a true change in gravity. Explain why repeated agreement is insufficient.

Course-specific review criteria

  • Derive the inverse-square clock dependence in both methods.
  • Identify a genuinely independent calibration rather than another use of the same clock.
  • Distinguish known generator truth from available real evidence.

Include calculations with units, source or dataset provenance, assumptions, competing explanations and limitations as relevant. The draft is saved but is not a locked response until submitted.

0/3 responses retained. No recorded feedback exposure for this task version. Earlier versions may already be familiar. Public inspectability still prevents certification of unfamiliarity.

41. Kinematics mixed case: reversing cart

A cart begins at x=3 m with v=4 m/s and constant a=−2 m/s². For 0–3 s find final position, displacement, distance, average velocity and average speed. A second observer moves at +1 m/s from the original origin: find the cart’s displacement in that frame. Explain all signs.

Course-specific review criteria

  • Locate the reversal at 2 s and split distance there.
  • Keep position, displacement and distance distinct.
  • Subtract observer displacement over the same three-second interval.
  • State the continuing-acceleration assumption.

Include calculations with units, source or dataset provenance, assumptions, competing explanations and limitations as relevant. The draft is saved but is not a locked response until submitted.

0/3 responses retained. No recorded feedback exposure for this task version. Earlier versions may already be familiar. Public inspectability still prevents certification of unfamiliarity.

42. Kinematics mixed case: equal endpoints, unequal histories

Two carts start at rest and reach 6 m/s in 4 s. One accelerates uniformly. The other waits 2 s then accelerates uniformly for the remaining time. Compare average acceleration, displacement and the evidence needed to distinguish them. Retry with the acceleration concentrated in the first half instead.

Course-specific review criteria

  • Use endpoint velocity change for average acceleration.
  • Use graph area rather than applying one constant-acceleration equation to both full intervals.
  • Describe an intermediate measurement capable of discriminating histories.

Include calculations with units, source or dataset provenance, assumptions, competing explanations and limitations as relevant. The draft is saved but is not a locked response until submitted.

0/3 responses retained. No recorded feedback exposure for this task version. Earlier versions may already be familiar. Public inspectability still prevents certification of unfamiliarity.

Retain a criterion-by-criterion human review

Reviewer identity and role are declarations, not authenticated credentials. Unsaved review fields below are lost on navigation. Review every criterion with an exact quotation, calculation or evidence citation and a next step.

Full-course mechanics and fluids evidence portfolio

Assemble original predictions, replayable virtual evidence and changed-case explanations across all eight content units. This is an authored learning workflow, not a claim that a learner has completed supervised practical work or an authorized AP course.

  1. Represent and define

    Select a novel mechanics or fluid claim, identify the system/frame/interval and represent it with a diagram, graph and symbolic relationships.

    Evidence to retain: First prediction retained before feedback; units, signs and a prerequisite explanation.

  2. Derive and test feasibility

    Use force, energy, linear/angular momentum or mass-flow balances as appropriate. Test a constraint before applying a shortcut.

    Evidence to retain: At least two contrasting captures and a rejected or threshold case, with replayable settings and an independent calculation.

  3. Investigate and challenge

    Develop a supplied-data inference with a bounded error calculation, an alternative explanation and an observation that could discriminate it. Address shared calibration explicitly.

    Evidence to retain: Data table, graph/fit or interval, uncertainty assumptions and an independent-reference plan.

  4. Demonstrate unfamiliar transfer

    Complete cumulative cases across kinematics/forces, energy/momentum, rotation/orbits, oscillations and fluid statics/dynamics without merely repeating worked solutions.

    Evidence to retain: Versioned task attempts, disclosure of viewed answers and reviewer comments; public answer access is not a secure examination.

  5. Separate practical and mastery gates

    Prepare a locally supervised practical proposal with risk assessment, variables, instrument calibration, repeat design and review criteria. Record actual execution only if it genuinely occurs under appropriate supervision.

    Evidence to retain: Proposed versus performed work explicitly distinguished; actual raw observations, supervision and independent review must be supplied externally, never synthesized by the app.

Project review criteria

  • Content coverage:68 original destinations plus investigations and cumulative feedback are authored; a page visit or prose submission does not establish mastery.
  • A qualified independent reviewer must evaluate unfamiliar learner reasoning and practical evidence; automated arithmetic checks alone are insufficient.
  • The current AP Physics1 framework calls for at least25% of instructional time in hands-on laboratory work. Virtual captures do not certify that time or replace local supervision.
  • No AP Course Audit approval, college credit, actual laboratory completion or secure examination status is granted. Browser/mobile/keyboard and evidence-migration validation are separate technical gates.

Retain raw-data identifiers, provenance, units, prior predictions, methods, calculations, competing explanations and safety boundaries. State explicitly when data are simulated, supplied or genuinely observed. This saved text cannot verify a real experiment; do not invent measurements or completed supervised work. Maximum 12,000 characters; retain larger evidence files separately and cite them.

A nonempty report is only a saved submission. First and revised reports remain separate and cannot be overwritten. A critique of the first report is required before retaining one revision.

Fresh transfer direction

Compare a new multi-stage mechanism and a new fluid/evidence problem. Defend each system boundary and explain how your conclusion would change if one essential assumption failed.

A human must supply the actual new task, evidence and conditions before the learner responds. The transfer-direction text is not itself an unseen assessment. Use the retained assignment form after the first project; exposed public task identifier: expanded-public:ap-physics1.

Science backups preserve each course's separate responses, exposure, rubric reviews and project history. Older backups do not reset attempts or erase known exposure. Divergent same-version immutable responses and incompatible same-version project histories are rejected rather than silently replaced; preserve both files for review.

Sources and boundaries
  • The AP laboratory requirement is at least 25% of instructional time. Current Course Audit guidance permits virtual labs or simulations with student data collection and analysis when circumstances prevent onsite laboratory access; science-educator supervision and retained student records are still required. Authored app content alone establishes neither performed laboratory time nor approval or independent mastery. No physical activity is requested; an educator must assess the applicable conditions and actual learner evidence.
  • Authored scope covers eight content units and two synthesis destinations; independently assessed learner performance and supervised practical evidence remain external gates.
  • No AP Course Audit approval, college credit, actual laboratory time or observed learner proficiency is claimed.
  • The optional numerical transfer is explicitly unsaved practice and does not award mastery.
  • Scientific review, shared integration and browser/mobile/keyboard checks must be recorded separately from unit-test results.

Original LearnAI explanations and tasks use the references for scientific scope. Any attributed dataset or image has its own declared provenance. Laboratory or field activity requires an appropriate educator-approved protocol; no hazardous real-world operation is required by the guided path.

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