A planet model appears to float in a Sengkang school planetarium. The first job in G3 Physics is not to admire it but to identify the forces: gravity acts downward, magnetic repulsion can act upward and a transparent guide or support may still carry part of the load. If you can draw the right force diagram, calculate weight and read a contact-force sensor without exaggerating its evidence, you have the foundation for the more difficult practical and explanation tasks.
This original guide develops K323 Physics from basic magnetism into force balance, fair testing and the limits of a public demonstration. It follows the planetarium thermal-control sequence ending in Vol 1213 but addresses a different question: apparent hovering is not proof of zero gravity or unsupported stability. Examples and numerical readings are invented for learning; none is a leaked or predicted SEC paper.
- Recall magnetic poles, induced magnetism and field patterns.
- Use W = mg and F = ma with labelled directions and valid assumptions.
- Infer one force from a static contact measurement without confusing it with weight.
- Design fair repeats, record anomalies and make defensible conclusions.
- Distinguish official G3 Physics content from an invented display setting.
1. Read the demonstration before trusting it
A model planet appears to hover above a plinth in a fictional school planetarium. Visitors see a gap, a guide, two magnets and a label that says “magnetic levitation”. A strong learner begins with a less dramatic question: what is actually supporting the object? If the planet rests on a transparent pin, sits inside a sleeve or touches a hidden stopper, gravity is not being balanced by magnetism alone. It is still a useful model, but it must be described accurately. Our goal is to draw forces, interpret changes, design a fair trial and decide exactly what conclusion a set of measurements allows. Every number in this chapter belongs to an original classroom scenario, not an actual exhibit or a forecast examination question.
2. Know where this fits in the 2027 G3 SEC
The 2027 SEC G3 Physics entry is K323, replacing the earlier reference code 6091. Its scheme has a 40-mark multiple-choice Paper 1 lasting one hour and worth 30%, an 80-mark structured and free-response Paper 2 lasting one hour 45 minutes and worth 50%, and a 40-mark practical Paper 3 lasting one hour 50 minutes and worth 20%. Students taking Combined Science must check their combination code rather than borrow these timings. The syllabus includes magnet properties, magnetic field patterns, induced magnetism, Newtonian forces, equilibrium and experimental evaluation. No official syllabus promises a “floating planet” task. The exhibit is a transfer context that lets familiar physics work together without pretending to be an extra syllabus topic.
3. Start with three observations, not three explanations
The student investigator receives three observations. The lower magnet is fixed to the base. The model planet contains a second magnet oriented so like poles face one another. A transparent vertical guide keeps the planet aligned and a force sensor reports contact force when the model is pressed towards the base. These observations should be written without inserting an explanation such as “magnetism cancels gravity”. The guide matters because lateral movement and friction could alter a result. “The measured contact force decreased” is a different statement from “the object became weightless”. By separating the visible arrangement, the instrument reading and the inference, students avoid a common examination error: treating an attractive account of what happened as if it were direct evidence.
4. Recognise the properties of magnets
A magnet has north and south poles. Like poles repel, while unlike poles attract. This is a relationship about magnetic poles, not a guarantee that any two pieces of metal repel. Iron is a magnetic material that can become magnetised by induction near a magnet; steel can retain magnetisation more readily and is often used for permanent magnets. A magnet also attracts some ferromagnetic objects that have no permanent north or south poles identified in the question. On a diagram, the relative directions and the object being acted upon matter. If a problem states that the upper model magnet is repelled upward by the fixed lower magnet, use that stated arrangement. Do not infer force direction solely from an artistic picture of the planet.
5. Draw magnetic fields carefully
Magnetic field lines indicate field direction and comparative field strength in a simplified representation. Outside a bar magnet, direction is conventionally drawn from north to south. Field lines do not cross, and closer lines indicate a stronger field in the conventional diagram. Between like poles, the pattern is not a straight bridge from one pole into the other; the field bends away from the region between them. An examiner can ask learners to recognise the correct pattern without expecting a calculation of magnetic force from it. For this fictional model, a clear annotated sketch is more valuable than elaborate shading. Label pole orientation, show field direction, and avoid inventing lines where the intended diagram gives insufficient information about magnet geometry.
6. Distinguish a field from a force
A field describes a region in which a magnetic object or current-carrying conductor may experience an interaction. A force is the push or pull acting on a particular object. The presence of a magnetic field does not tell us the numerical force on our planet model without suitable measurements and a specified arrangement. In a written answer, say “the upper magnet experiences an upward repulsive magnetic force” rather than “the magnetic field is upward”. The field itself may have a complicated geometry, especially around two real magnets. If the question only asks for the direction of resultant force, identify forces on the one body first. This careful distinction helps students in electricity, electromagnetism and mechanics, where field and force are also easily confused.
7. Define mass and weight before balancing forces
Our model has a stated mass of 0.20 kg. Taking gravitational field strength as 10 N/kg for the practice question, its weight is W = mg = 0.20 × 10 = 2.0 N. Mass is measured in kilograms and relates to the amount of matter and resistance to a change in motion. Weight is a gravitational force and is measured in newtons. The model does not lose mass when magnets support some of its weight. On a force diagram, weight acts downward, while the repulsive magnetic force acts upward. A learner who writes “the magnet reduces the planet’s gravity” has mistaken a reduced contact reading for a changed gravitational interaction. Repair the concept before doing more arithmetic.
8. Draw a free-body diagram for one object
Choose the model planet as the object, then draw only forces acting on that planet. Put weight downward. Put magnetic repulsion upward. If the planet remains in contact with a support, add an upward contact or normal reaction. If a guide presses sideways, there may also be lateral reaction forces; if the model slides, friction may arise. Do not put the force exerted by the planet on the base on the planet’s own diagram: it belongs to the base. State any simplifications made, such as negligible guide friction. Good diagrams are not works of art. They show the body, force arrows, clear labels and directions consistent with the question. A later equation should match precisely the diagram being used.
9. Use equilibrium only when equilibrium is justified
For a motionless planet resting against a support, the resultant force is zero. With downward weight 2.0 N, measured upward contact reaction 0.8 N and no significant vertical friction, the upward magnetic force is 1.2 N because magnetic force plus contact reaction balances weight. Written as an equation: Fmag + N = W, giving Fmag = 2.0 − 0.8 = 1.2 N. This is a calculation made possible by the stated simplified force balance; it is not a general formula for two magnets. The condition “at rest” matters. If the model is accelerating upward or downward, the forces do not balance and the equilibrium equation cannot be used unchanged.
10. Interpret the contact sensor correctly
Suppose the same planet produces a normal reaction of 0.5 N at a smaller separation, under otherwise comparable conditions. In the simplified static model, magnetic repulsion is 2.0 − 0.5 = 1.5 N. The sensor reads less, but the object still has weight 2.0 N. This is a strong conceptual test. A scale or force sensor can measure its particular contact force, not automatically the entire gravitational force when additional forces are present. If the apparatus contains a guide, support cable or hidden magnets, its force balance changes. Do not equate a single sensor reading with the whole physical story. Name what the sensor directly measures and what the learner infers from other information.
11. Recognise the boundary of a floating claim
A demonstration may be called “floating” in everyday speech even when a transparent guide constrains the object. Physically, the important question is whether the object remains in equilibrium without contact support or guidance. Magnetic repulsion may supply an upward force but does not, by itself, establish stable support against sideways displacement or rotation. A photograph cannot settle that question. This chapter therefore treats the visible guide as a material limitation, not an embarrassing detail to hide. Strong scientific writing can acknowledge an impressive phenomenon and still set limits on its interpretation. An appropriate caption could say that repelling magnets reduce the load on a support under controlled conditions, while the transparent guide maintains alignment.
12. Identify variables for a fair investigation
The independent variable might be the separation between magnet faces. The dependent variable might be the measured normal reaction while the model remains stationary. Important controlled variables include magnet identity, magnet orientation, model mass, apparatus alignment, sensor position, and whether the same support and guide are used. A good practical plan also states how separation is measured: from the defined opposing faces, along the central axis, not from an arbitrary decorative surface. Repeating each reading helps reveal variability. If a magnetic field is altered by nearby metal objects or another magnet is introduced between trials, the changed reading has more than one possible explanation. The cleaner the comparison, the easier the conclusion.
13. Explain why separation matters without inventing a formula
In many simple repelling-magnet arrangements, interaction changes as the magnets move apart. The precise relationship depends on magnet shape, orientation and geometry; the G3 guide does not need a universal inverse-square formula for this particular setup. A fair response can describe the trend found in a table without claiming that doubling separation must quarter the force. Imagine three steady contact readings: at 2 cm the contact is 0.4 N, at 3 cm it is 0.8 N and at 4 cm it is 1.2 N. The inferred upward magnetic forces are 1.6, 1.2 and 0.8 N respectively. These invented data show decreasing repulsion with increasing separation across the tested interval. Beyond the measurements, resist extrapolation.
14. Convert an observation into a two-column table
Students often rush into conclusions before labelling a table. One column should show magnet separation in centimetres, with the definition and unit given once in the heading. Another should show contact force in newtons. If magnetic force is inferred from a known weight, label the third column as “inferred upward magnetic force”, not “measured magnetic force”. That single word prevents a serious ambiguity. Arrange separation values in a sensible order and include enough decimal places to reflect the instrument’s resolution. A difference between 0.40 N and 0.4 N may or may not matter depending on what the instrument actually displays. Precision in a table should follow the instrument, not a wish to look scientific.
15. Check the sensor at zero and at a known load
Before using a sensor, establish what zero means. An unloaded reading should be near the specified zero; if an offset remains, the learner should not silently subtract it without knowing whether the procedure allows correction. A known reference load can help reveal a calibration problem, though the apparatus instructions control what may be done. If a 2.0 N object yields 2.1 N in a simple no-magnet reference check, all subsequent interpretations need caution. That small discrepancy may arise from calibration, alignment or reading variability. A reliable practical explanation records the issue and proposes a reasonable check. The aim is not to make every number exact but to prevent systematic error from masquerading as a physical trend.
16. Distinguish repeated readings from repeated predictions
Consider a trial at 3 cm yielding 0.80, 0.82 and 0.78 N. These are measured contact readings, so their mean is 0.80 N. Under the simplified static model, the corresponding inferred magnetic force is 1.20 N. It would be misleading to write that three independent magnets all produced 1.20 N; the readings are repeat measurements on one particular setup. Range 0.04 N is one useful description of spread, but it is not automatically a formal uncertainty interval or proof of perfect calibration. A scientist seeks both repeatability and validity. Repeating a biased method five times can produce tightly grouped wrong answers. The best plan therefore tests both the instrument and the controlled variables.
17. Explain attraction and repulsion in comparisons
Imagine a student changes the upper magnet’s orientation. The model may now experience attraction toward the lower magnet rather than upward repulsion. Depending on the support and guide, its measured contact force could increase, not decrease. A strong answer names the direction on the model rather than asserting that magnets always lift. It also asks whether the model remains motionless; an attractive configuration can pull it into contact with the support, while a repulsive one may reduce contact force. Students should be able to explain both configurations with one method: list forces, establish directions, decide whether equilibrium applies and compare what the sensor measures. Never label a trial as “better” before defining the quantity being improved.
18. Describe induced magnetism without mixing up materials
A small iron component placed near the magnet can become temporarily magnetised and experience attraction. This does not make iron equivalent to a second permanent magnet. Permanent and induced magnetism have different explanations and, in some cases, different behaviour after the external field is removed. For a fair comparison, keep additional magnetic material away from the apparatus unless its effect is the variable deliberately being tested. In everyday cases a metal stand, steel screw or nearby tool can disturb a demonstration. A written exam may use such an unfamiliar context to test whether students recognise induced magnetism. Avoid claiming that aluminium, copper and iron have identical magnetic responses merely because all are commonly called metals.
19. Use Newton’s first and second laws in context
If the model remains motionless, its net force is zero even when several large forces act on it. Zero resultant force is not the same as no forces. If the resultant force is not zero and the body is free to move, acceleration follows the direction of the resultant force according to F = ma. Suppose upward magnetic repulsion becomes 2.4 N while downward weight is 2.0 N and all other vertical forces are negligible. The idealised net force is 0.4 N upward and acceleration is 0.4/0.20 = 2.0 m/s² upward. In a real guided apparatus, contact and friction forces may prevent this acceleration; the calculation must not ignore forces present in the scenario.
20. Keep action–reaction pairs on different bodies
The lower magnet pushes the upper magnet upward. The upper magnet pushes the lower magnet downward with an equal-magnitude, opposite-direction interaction. Those two forces form an action–reaction pair because they act on different objects. They do not cancel on the upper planet. The planet also experiences its weight; Earth experiences the equal and opposite gravitational interaction from the planet, though that is usually outside the simplified diagram. Students lose marks when they put both members of an action–reaction pair on the same diagram and conclude that every body must be at rest. For any named force, write “object A on object B” and then identify the corresponding force “object B on object A”. That habit settles most confusion.
21. Do not infer stability from one steady photograph
A model can appear steady for a second while still being easily displaced. An assessment of stability needs observations under defined perturbations and a clear distinction between movement, restoring tendencies and external guidance. We are not using the fictional exhibit as evidence that a particular construction is safe for public use. Classroom magnets can snap together, pinch fingers or damage sensitive objects; teachers and trained operators should control equipment choices. For examination practice, ask whether the description provides enough information to establish an unassisted equilibrium. If not, the correct response is to say what remains unknown. Saying “insufficient evidence” is not a weak answer when the source genuinely omits a necessary condition.
22. Choose graph axes with purpose
A useful graph places separation on the horizontal axis and contact force on the vertical axis, with units and a scale that uses the available space. Plot individual points or means as instructed. Unless a model is justified, do not force a straight line through a visibly curved relation. The slope of a graph can be discussed descriptively, but a numeric straight-line gradient should not be treated as a physical law for magnets. When several readings are taken at one gap, show their spread appropriately or explain how a mean was calculated. If one reading is far from the others, first check for a transcription error or uncontrolled change. A neat graph is an aid to reasoning, not an excuse to hide anomalous data.
23. Separate causal explanation from correlation
A decreasing contact force as separation decreases is consistent with stronger upward repulsion. Yet correlation within three observations does not eliminate other influences, such as changing guide friction or sensor contact geometry. A causal explanation needs a controlled method and an appropriate physical mechanism. In an exam response, phrase your conclusion as “for the tested arrangement, reducing the separation was associated with a smaller normal reaction, consistent with greater magnetic repulsion”. That wording reports the evidence honestly. It also tells the reader what has not been established: a precise universal force law, stable unsupported levitation or reliability across all magnet types. Carefully qualified scientific language is often shorter and stronger than a confident but unjustified claim.
24. Work with different gravitational field strengths
The SEC Physics syllabus expects learners to understand gravitational field strength and weight, so a planetarium provides a natural transfer question. If the same 0.20 kg model were imagined near the lunar surface with g approximately 1.6 N/kg, its weight would be 0.32 N. That is a hypothetical calculation, not a change produced by placing it inside a planetarium. An exhibit sometimes uses “Moon gravity” to describe a simulated setting; the physical model on Earth still experiences Earth’s gravitational field. Make the distinction explicit. A question may ask how a modelled weight changes if g changes, but its laboratory force sensor reading on Earth must be interpreted using the forces actually present.
25. Read a diagram of unlike poles
An exam diagram may show one magnet above another and ask whether an initially supported object moves closer or farther when released. If unlike poles face, magnetic attraction is toward the lower magnet. If like poles face, the repulsion is away from it. That conclusion assumes other forces and constraints do not dominate. Do not try to decide movement solely from pole names without identifying where each magnet is positioned. With a bar magnet, the north pole on the upper magnet facing the north pole of the lower magnet creates repulsion between facing poles. Sketching two labelled bars is often faster and safer than verbal guesswork. An answer that includes force direction receives more physical meaning than a bare “up”.
26. Understand what the practical paper actually rewards
K323 Paper 3 is not a contest to create the most striking demonstration. It examines planning, manipulation and observation, presentation of data, and analysis and evaluation. The official practical description includes both compulsory experiments and opportunities to use findings for reasoned conclusions. The exact apparatus varies by year, so this fictional guided-magnet apparatus is training rather than promised exam equipment. To prepare, rehearse general skills: identify a variable, describe a safe repeatable method, write a table with units, plot a graph, recognise anomalies and propose a specific improvement. Vague advice such as “be more careful” rarely explains how a source of error is controlled.
27. State a useful improvement instead of a slogan
Suppose alignment changes whenever the gap is adjusted. An improvement is to clamp the fixed magnet securely and adjust separation using a marked vertical mechanism while preserving orientation, rather than moving the entire base by hand. If friction may affect the measurement, repeat in conditions that allow guide contact to be checked or independently characterised. If someone proposes increasing the number of readings, say where and why: for example, take three readings at each specified gap to estimate repeatability. Do not list improvements that address problems the experiment never had. Match one limitation to one physical change and one expected benefit. This is a transferable skill across Physics, Chemistry and Biology practical work.
28. Use units as a reasoning tool
Force is measured in newtons, mass in kilograms, separation in centimetres or metres, and gravitational field strength in N/kg. When calculating W = mg, keep a compatible unit system. A model weighing 200 g has a mass of 0.200 kg; multiplying 200 by 10 as if grams were kilograms gives an impossible 2000 N. If a graph uses centimetres, keep the horizontal label explicit and convert only where a calculation requires metres. Decimal places should reflect a legitimate level of precision. Unit checking cannot prove that a scientific explanation is complete, but it can expose many implausible answers quickly, especially when several measurements and inferences appear in the same question.
29. Worked question: infer a missing force
A 0.15 kg planet model rests in a guide with negligible vertical friction. The measured contact reaction is 0.45 N. Taking g = 10 N/kg, find magnetic force. First calculate weight: 0.15 × 10 = 1.50 N downward. At rest, net vertical force is zero, so 0.45 N upward from the contact plus magnetic force upward balances 1.50 N downward. Magnetic force is 1.05 N upward. State the direction in the final answer. If the student instead subtracts mass from force, the quantities are incompatible. If the guide supplies an additional upward force, the information is no longer sufficient for this calculation without that force. The assumptions are as important as the arithmetic.
30. Worked question: test a change in reading
The same planet’s contact reaction falls from 0.45 N to 0.30 N when the gap decreases. Assuming all forces and the state of rest are still described correctly, inferred magnetic repulsion rises from 1.05 N to 1.20 N. The change is 0.15 N. We can conclude that the model’s contact load has decreased and the inferred upward magnetic contribution has increased. We cannot conclude that the magnet itself has strengthened permanently, because nothing indicates a change in magnet material or magnetisation. The conclusion is about an interaction under changed geometry. This is a good example of how a precise calculation can coexist with a carefully limited physical claim.
31. Worked question: spot the false force diagram
A student draws four arrows: weight downward, magnetic repulsion upward, support reaction upward and “planet pushes on base” downward. The last arrow should not be on the planet’s free-body diagram, because it represents a force acting on the base. Remove it and reassess equilibrium. A second student writes that magnetic force and reaction force cancel automatically because they point in the same direction; that is also wrong. Forces pointing in the same direction add. In the correct simplified model, weight balances the sum of those upward forces. Examination questions often award credit for a correct body choice and force direction before numeric work. Practise identifying the object first to keep diagrams disciplined.
32. Worked question: interpret an anomalous trial
Three contact readings at a 3 cm gap are 0.78, 0.81 and 1.35 N. A student deletes 1.35 without comment. A better response notes that the third reading is substantially different and checks whether the upper magnet was misaligned, the guide stuck, the sensor was zeroed incorrectly or the gap was recorded wrongly. If the experiment can be repeated safely under teacher supervision, collect another reading while keeping the method consistent. The original outlier should remain documented until there is a defensible reason to exclude it. An anomaly may indicate error, but it may also reveal that the stated model is incomplete. Sound practical judgement does not require every dataset to look tidy.
33. Original multiple-choice practice
Question: a motionless model experiences weight 2.0 N down, magnetic repulsion 1.3 N up and a support reaction 0.7 N up. Which statement is correct? A: the planet’s weight is 0.7 N. B: the resultant vertical force is 0 N. C: the magnetic force equals the weight. D: there is no gravitational force. Answer B. The upward forces total 2.0 N and balance weight. The question is deliberately simple: it checks whether a student understands equilibrium rather than whether they can calculate quickly. In exam preparation, explain why each wrong option is wrong. Eliminating A and D requires mass–weight reasoning; eliminating C requires comparing actual force magnitudes.
34. Original structured-response practice
A classroom exhibit uses like poles facing and a transparent guide. At four gaps, the mean contact forces are 0.30, 0.55, 0.90 and 1.20 N. The planet’s weight is 1.80 N. Tasks: state the independent variable; identify two controls; infer magnetic force at each gap; describe the trend; propose a reason why the model cannot be advertised as “unsupported”; and name one additional measurement needed for a stronger stability claim. Correct forces are 1.50, 1.25, 0.90 and 0.60 N upward respectively, assuming static equilibrium and no other vertical forces. The trend is decreasing repulsion with increasing gap for these data. A stronger answer refers to guide contact and disturbance tests rather than imagining unsupported stability.
35. Mark the explanation, not just the answer
A worked answer with the correct four inferred forces can still be incomplete if it does not explain that the model remains stationary or leaves out which force is directly measured. To self-mark, give separate attention to choosing forces, calculating weight, balancing directions, recording units, describing the trend and evaluating a limitation. A useful feedback note identifies the precise missing link: “I found the right subtraction but did not state static equilibrium” or “I called a calculated value a direct sensor reading”. Specific corrections are easier to practise than broad comments such as “understand Physics”. When repeating the problem, change the model mass and the support reading so that success shows transfer, not memorised numbers.
36. Compare a Physics explanation with a visitor caption
The scientific explanation may need several lines: a specified contact force, upward repulsion, downward weight, a condition of rest and limitations from the guide. The visitor caption should be shorter but must not contradict it. An appropriate example is: “Opposing magnetic poles reduce how strongly this model presses on its support. A clear guide keeps the model aligned during the demonstration.” An inappropriate claim is: “Magnets cancel gravity, making the planet weightless.” English clarity and Physics accuracy support one another here. Students should learn to translate between technical and public language without smuggling a false scientific assertion into the simpler wording. This prepares the next Mathematics and English volumes in the series.
37. Distinguish a school model from engineering approval
The numbers and design details in this guide are fictional. They do not establish that an installation is suitable for children or visitors, nor do they provide instructions for constructing unsupported magnetic levitation. Real devices may involve pinch hazards, unstable motion, sensors, hidden supports and requirements assessed by qualified people. The learner’s job is narrower: evaluate the information placed in an examination-style scenario. When the source leaves safety data absent, say so. Good science does not treat a classroom experiment as certification of a public device. Similarly, a calculated equilibrium for one idealised instant does not guarantee operation when the mass, alignment or nearby metal objects change.
38. Build an efficient revision sequence
For the first practice session, review pole interactions and field directions using simple diagrams. In the second, practise weight and free-body diagrams without any magnets, then add magnetic force. In the third, use a table of contact readings to calculate inferred forces and recognise an anomaly. In the fourth, answer a short evaluation prompt on control variables and public claims. Keep a small error log: confusing weight and contact force; placing action–reaction pairs on one body; using equilibrium when acceleration is present; or claiming that a visual effect proves stability. Each mistake calls for a different repair. Working through that sequence is more effective than repeating the entire chapter without diagnosing the difficulty.
39. How to answer under time pressure
Read the command word before working. “State” usually calls for a brief fact. “Explain” requires a reason connected to the scenario. “Calculate” needs a mathematical route and units. “Suggest” invites a plausible, syllabus-grounded inference from the provided information. For a multi-part question, handle the straightforward force diagram and mass–weight relation before the evaluation paragraph. Do not fill the answer space with irrelevant details about space travel simply because the setting is a planetarium. The context should guide which physics to use, not distract from it. Leave enough time to check arrow directions, whether the model is moving and whether the value reported is measured or inferred.
40. Questions students frequently ask
Does “floating” mean the object has no weight? No; weight due to gravity still acts. Can like poles create repulsion? Yes, but the total motion depends on all the forces and constraints. Is a field pattern a numerical force graph? No. Why does a contact reading fall? Because another upward contribution may reduce the contact load under the stated conditions. Does one photograph prove stable unsupported levitation? No. Is this a confirmed 2027 examination topic? No: it is original practice aligned with selected syllabus outcomes. Should Combined Science students use K323 timings? Only if they are registered for standalone K323 Physics. Otherwise, consult the applicable combined-science syllabus and papers.
41. A stronger extension for confident learners
Consider a model with mass 0.20 kg and a downward guide friction force of 0.10 N while the planet is moving upward. An upward magnetic force of 2.60 N acts and the support reaction is zero. Weight is 2.00 N down, so the resultant is 2.60 − 2.00 − 0.10 = 0.50 N upward; acceleration is 0.50/0.20 = 2.5 m/s² upward. Notice why equilibrium subtraction from a static contact trial is not appropriate here. The added friction changes both the force diagram and the calculation. This extension is not intended as a safe construction exercise. It tests whether learners can assemble a consistent Newtonian model when the assumptions change.
42. Check what is directly observable in the next trial
Suppose the guide is opaque rather than clear. Can the student still conclude that the model has no contact? No, not from appearance. Could an alternative sensor arrangement distinguish support force from magnetic lift? In principle, yes, if its reading is properly defined and its influence on the setup is considered. Could adding more trials establish generality for all magnet combinations? Not without a broader sample and controlled comparisons. These questions train evidence literacy. A convincing answer is not merely a number; it tells a reader how the number was obtained and where it stops being informative. The same distinction will matter in the Mathematics load-model chapter and in a later written judgement about the exhibit.
43. The next step across English, Mathematics and Science
To continue this four-part study, use the next volume to model permissible loads and test quantitative constraints; then use an English continuous-writing task to turn a disagreement about the exhibit into a coherent narrative rather than a technical report. Finally, compare the science, numerical findings and public wording in an integrated evidence decision. These links are between learning tasks, not between SEC papers: English, Mathematics and Physics remain separate official examinations. Students moving up from the primary syllabus can revisit the Sengkang PSLE learning guide for basic observations, forces, graphs and clear explanations, then progress to G3 force diagrams, bounded claims and independent checking. The principle is to strengthen the first weak link rather than hurry through four chapters.
Official references and connected learning routes
Check the SEAB 2027 G3 syllabuses directory and 2027 SEC G3 Physics K323 syllabus for authoritative assessment details. The earlier magnetism foundations volume owns general pole and field-pattern revision, while this chapter owns the floating-planet force-balance case. Follow the Vol 1213 thermal-control evidence review for the previous case, the Sengkang G3 English, Mathematics and Science guide for subject pathways, and the PSLE Learning Guide for the earlier foundation. Use the exact G3 syllabus registered by your school; combined science has different entries from K323.
