To learn IB Diploma Programme Physics at Standard Level (SL) and Higher Level (HL) quickly and correctly, begin with what a physical quantity means, how it changes and what evidence could show that your explanation is right. Physics connects motion, heat, waves, electricity and modern science through a few powerful ideas. These eduKateSG Quick Notes follow the IB Physics curriculum first assessed in 2025, which has five organising themes and uses energy, particles and forces as connecting concepts. Rather than memorising equations in isolation, you will learn a small method for drawing a model, calculating carefully and explaining the result.
- Know your level: separate SL learning outcomes from HL extensions using the official guide.
- Think in three concepts: ask what forces act, how energy is transferred and what particles are doing.
- Choose a representation: a force diagram, graph, circuit, field sketch or equation.
- Track units: include correct SI units, signs and appropriate precision.
- Test with evidence: read graphs, describe uncertainties and practise scientific investigations.
- Learn the assessment: Papers 1 and 2 plus the individual scientific investigation.
First, choose one everyday event. When a ball is released from rest and falls, its speed changes. Near Earth’s surface, and when air resistance is small enough to neglect, the ball has approximately constant downward acceleration. If it starts from rest, after 2 seconds its speed is about v = gt = 9.81 × 2 = 19.6 m/s downward. Write down the conditions before calculating. Without them, the equation could be used where it does not apply. Physics begins with a model and assumptions, not with the first formula you remember.
Second, connect the calculation to a graph. On a velocity–time graph, uniform acceleration appears as a straight line with constant gradient. The gradient represents acceleration, while the signed area under the graph represents displacement. For an object starting from rest and accelerating at 2 m/s² over 3 seconds, final velocity is 6 m/s and the triangular area is ½ × 3 × 6 = 9 m. The equation, line and geometric area describe one motion in different ways. Learn to switch between them and the topic becomes much easier.
Third, make the problem slightly less familiar. What if the object’s initial velocity were 4 m/s? Then under the same constant acceleration of 2 m/s² for 3 seconds, the final velocity would be 4 + 2 × 3 = 10 m/s, and displacement would be average velocity × time = (4 + 10)/2 × 3 = 21 m. A graph would have a rectangular contribution from the initial velocity plus a triangular contribution from the acceleration. This is how you practise correctly: change one condition, adapt the reasoning and check that the model still fits.
The five themes in the IB Physics syllabus
The revised IB Physics programme groups its content around five organising themes. The themes do not dictate a single teaching order, and they are connected through forces, energy and particles. Use them as the five main sections of your notes, then link each new equation to the physical question it answers.
- A — Space, time and motion: kinematics, forces, momentum, work, energy and power; further mechanics and relativity at the appropriate level.
- B — The particulate nature of matter: thermal energy transfers, the greenhouse effect, gas laws, thermodynamics, electric current and circuits.
- C — Wave behaviour: wave models and, where specified, simple harmonic motion, interference, resonance and the Doppler effect.
- D — Fields: gravitational, electric and magnetic fields, and further electromagnetic effects at the appropriate level.
- E — Nuclear and quantum physics: atomic structure, radiation, fission, fusion, stars and quantum ideas where required.
Some topics have additional HL content; others are HL-only. For example, the current guide identifies special relativity, selected quantum physics and induction topics as requiring HL-only study. Do not assume every topic name means identical depth for SL and HL. Your school’s learning schedule should be checked against the current guide’s exact symbols and learning outcomes.
SL and HL: the scope is different
The IB recommends 150 teaching hours for SL and 240 teaching hours for HL. This includes an experimental programme and the assessed scientific investigation. HL does not merely require faster arithmetic; it includes additional ideas and greater conceptual depth. Both levels require scientific reasoning, mathematical accuracy and interpretation of data, but HL applies these skills across a wider set of physics concepts.
The assessment explained in a simple way
For both SL and HL, external papers contribute 80% of the final grade and the individual scientific investigation contributes 20%. The current assessment model has Paper 1A, Paper 1B and Paper 2 within two examination components; there is no separate Paper 3 in the current syllabus. Paper 1 combines multiple-choice questions with data-based questions, while Paper 2 has short-answer and extended-response questions.
- SL Paper 1: 1 hour 30 minutes, 45 marks, 36% of the final grade.
- SL Paper 2: 1 hour 30 minutes, 55 marks, 44%.
- HL Paper 1: 2 hours, 60 marks, 36%.
- HL Paper 2: 2 hours 30 minutes, 90 marks, 44%.
- Scientific investigation: individual research investigation, internally marked and externally moderated, 20% at both levels.
The official Physics data booklet is available under the permitted examination arrangements, and calculators are permitted subject to IB rules. Do not let those resources replace understanding: you must still select the correct relationship, recognise its assumptions and explain what your answer means. Your IB coordinator will provide the examination-year instructions and any permitted-material changes.
Worked example: use Newton’s second law
A trolley of mass 3.0 kg experiences a net horizontal force of 12 N. Newton’s second law gives F = ma, so its acceleration is 12 ÷ 3.0 = 4.0 m/s² in the direction of the net force. A common mistake is using the magnitude of one applied force while ignoring friction. If the trolley has a 12 N driving force to the right and a 3 N resistive force to the left, the net force is only 9 N, so acceleration is 3.0 m/s² to the right.
Draw a free-body diagram and show the forces in their actual directions. Forces can be present even when the object moves at constant velocity: it is the resultant force, not the existence of any force, that determines acceleration. This idea carries into circular motion, fields, oscillation and more advanced dynamics.
Worked example: distinguish energy and power
Suppose a motor transfers 600 J of energy in 5.0 s. Its average power is 600 ÷ 5.0 = 120 W. Energy measures an amount transferred; power measures the rate of that transfer. If a question instead asks for efficiency, you need useful output energy or power as well as total input energy or power, with compatible quantities. A higher power rating does not automatically imply greater efficiency.
A useful cross-topic question is: where does the input energy go? In a real machine, some energy is transferred into less useful thermal or sound forms. Energy conservation still applies; low efficiency means only a proportion reaches the intended output.
Worked example: interpreting waves
For a wave with frequency 20 Hz and wavelength 0.75 m, wave speed is v = fλ = 20 × 0.75 = 15 m/s. Frequency counts cycles per second, wavelength measures one spatial cycle and speed describes how the wave disturbance travels. If the wave enters another medium, the propagation speed can change. Think carefully about what happens to frequency and wavelength in the specific situation before applying a rule.
Worked example: uncertainty needs a physical explanation
Suppose five measurements of the time taken for an object to complete an oscillation are close but not identical. The variation could come from timing resolution, inconsistent starting conditions or human reaction time. Repeated readings can help estimate random scatter, but they do not automatically remove a systematic error in the measuring method. State which uncertainty matters and how it affects the conclusion.
The best experimental response is not simply ‘repeat the experiment more’. Explain why a particular change improves the investigation. Timing multiple oscillations rather than one, for example, can reduce the proportionate effect of a fixed start/stop reaction-time error when a period is found by dividing the total time by the number of oscillations.
The scientific investigation: begin with a narrow question
The scientific investigation is an individual assessed task worth 20% of the grade. Under the current guide, it is marked out of 24, and the report has a maximum length of 3,000 words. A good research question specifies an outcome you can measure, a factor you can vary and conditions you can control. It should be safe and feasible with the equipment, time and supervision available.
- Define: a precise physical relationship and measurable dependent variable.
- Plan: select apparatus, a suitable data range and controls.
- Collect: record readings, units and meaningful measurement uncertainties.
- Analyse: use relevant graphs, calculations and appropriate uncertainty treatment.
- Conclude: answer the original question using the evidence.
- Evaluate: identify specific limitations and justified improvements.
For example, investigate how the length of a simple pendulum relates to its period for sufficiently small oscillations under supervised laboratory conditions. Measure several lengths, time multiple cycles and record the relevant uncertainty. The idealised relationship predicts that period squared is proportional to length when assumptions are satisfied. A useful investigation checks the range over which the model fits; it does not merely print a straight line and declare success.
How to answer IB Physics data questions
- Read the axes: identify units, scales, independent and dependent quantities.
- Describe first: say what increases, decreases or remains constant.
- Calculate with care: show the relationship and a correctly sized result.
- Interpret: connect the number or trend with a physical mechanism.
- Evaluate when needed: state uncertainty, assumptions and meaningful limitations.
If a graph is curved, do not automatically fit a straight line through it. Ask which mathematical transformation or model could express the relationship, and whether that choice has a physical basis. A numerical fit can describe observed data without establishing the correct causal mechanism.
Your 25-minute IB Physics learning routine
- Minutes 0–4: recall one definition, quantity or physical principle without notes.
- Minutes 4–9: draw the scenario, axes or free-body diagram.
- Minutes 9–16: solve a numerical example and show the units.
- Minutes 16–22: practise a related data, explanation or experimental-design question.
- Minutes 22–25: check the first wrong step and plan one new example for tomorrow.
Common mistakes and how to fix them
- Substituting values without a model: name the assumptions and variables first.
- Confusing speed and velocity: check whether direction is required.
- Using an applied force instead of the net force: draw all relevant forces.
- Leaving units or significant figures out: write them at every stage.
- Claiming a graph proves a cause: distinguish data from interpretation.
- Working with an obsolete Paper 3 syllabus: use the first-assessment-2025 structure.
- Studying HL-only topics as mandatory SL content: check the official topic markings.
Mini-test: try these before checking
- A 4 kg object has a net force of 10 N. Find its acceleration.
- An electrical device transfers 900 J in 30 s. What is its average power?
- A wave has frequency 5 Hz and speed 20 m/s. Find its wavelength.
- What percentage of the IB Physics final grade comes from the scientific investigation?
Answers
1. a = F/m = 10/4 = 2.5 m/s². 2. P = E/t = 900/30 = 30 W. 3. λ = v/f = 20/5 = 4 m. 4. 20%. Each numerical answer has a unit because it describes a physical quantity.
Your next small step
Choose a topic you cannot yet explain from memory. Write one question, sketch the model, identify the relevant physics, calculate an example and check the assumptions. Review it tomorrow with a different context. Physics becomes quicker when you see the same principles working across motion, energy, waves and fields.