QCE Physics IA2 student experiment: The 2026 guide

Study guide16 min readUpdated 21 Jun 2026

Quick answer

QCE Physics IA2 student experiment is a 2000-word scientific report on a student-designed Unit 3 investigation; top-band reports use a specific research question with explicit theoretical basis, detailed methodology with justified design choices, substantial data with uncertainty propagation through all calculations, linearised graphs with min/max slope gradient uncertainty, and a discussion naming specific uncertainty sources tied to specific experimental steps.

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What this guide is for
Common contexts
Scientific report structure
Research question
Hypothesis
Methodology
Data and uncertainty
Analysis
Discussion
Conclusion
Check your knowledge

What this guide is for

QCE Physics IA2 is a major Unit 3 assessment. The student-designed experiment, scientifically reported, is worth 20 percent of the subject result. This guide covers common contexts, report structure, and the moves that secure top band.

Common contexts

Projectile range: Verify $R = v^2 \sin(2\theta) / g$ . IV: launch angle. DV: range. Use a marble launcher or spring-loaded cannon at fixed initial velocity.
Conical pendulum: Verify $F = m v^2 / r$ or $T = 2\pi \sqrt{L \cos\theta / g}$ . IV: angle. DV: period or required force.
Simple pendulum: Verify $T = 2\pi \sqrt{L/g}$ and derive $g$ . IV: length. DV: period. Linearise via $T^2$ vs $L$ .
Faraday induction: EMF vs rate of flux change. IV: magnet drop speed or coil turns. DV: induced EMF.
Transformer: Turns ratio vs voltage ratio. IV: secondary turns. DV: secondary voltage at fixed primary AC input.

Scientific report structure

Title: Specific.
Abstract: ~150 words.
Introduction

Research question.
Theoretical framework (relevant Unit 3 physics).
Hypothesis with prediction.
Aim.

Method.

Variables (IV with range, DV with precision, controlled).
Apparatus (labelled diagram).
Procedure.
Risk assessment.

Results.

Raw data table.
Processed data with uncertainty.
Graphs (linearised).

Analysis.

Best-fit line, gradient, intercept with uncertainty.
Comparison to theory.

Discussion.

Uncertainty sources.
Limitations.
Improvements.

Conclusion. Direct answer to research question.

References.

Research question

Specific, testable. Example: "How does the angle of release of a projectile fired from a horizontal surface affect its horizontal range, for launch angles between 15 and 75 degrees in 10-degree intervals, with initial velocity controlled at 5.0 plus/minus 0.2 m/s?"

The strong version specifies ranges, increments, and the controlled variable.

Hypothesis

With theoretical basis. "Range will be maximum at 45 degrees, with $R = v^2 \sin(2\theta) / g = (5.0)^2 \sin(2\theta) / 9.8 = 2.55 \sin(2\theta)$ m." Predicts the specific functional form.

Each stage of the workflow services a different ISMG criterion; the named hypothesis sets up the linearisation that determines the gradient, and the gradient is the experimental value the conclusion criterion reports.

Methodology

Detailed enough to replicate.

Labelled diagram. Step-by-step procedure. Risk assessment naming hazards and mitigation.

Justify design choices. Why these increments? Why this many trials per IV value?

Data and uncertainty

Raw data table: Each measured value with its uncertainty and units.
Processed data: Derived values with propagated uncertainties.
Graphs: Linearised where applicable. Uncertainty bars on both axes. Best-fit line plus min/max slope lines.

Analysis

Gradient and intercept with uncertainty.

Compare to theoretical prediction.

For pendulum: gradient of $T^2$ vs $L$ should be $4\pi^2/g$ . Calculate $g$ from gradient; compare to 9.8 m/s $^2$ .

Discussion

Name specific uncertainty sources tied to specific steps.

Distinguish random (varies trial to trial) from systematic (consistent bias).

Discuss whether results agree with theory within uncertainty.

Suggest improvements specific to the experimental procedure.

Residuals scattering randomly evaluate the model favourably under the IA2 evaluation criterion; a curved residual pattern is a flag the discussion must name and quantify.

Conclusion

A direct answer to the research question. Include experimental value with uncertainty. Compare to theory or accepted value.

Check your knowledge

Six questions covering hypothesis design, equipment limitations, and reproducibility for the IA2 student experiment. ISMG criteria are signposted in the solutions. Three significant figures and units throughout.

State the difference between a hypothesis and a research question in IA2 terms, then convert the hypothesis "Heavier magnets induce a larger EMF" into an IA2-grade research question tied to Faraday's law. (3 marks)
A student uses a stopwatch ( $\pm$ 0.20 s reaction time) to measure the period of a 1.00 m pendulum at five amplitudes (5, 10, 20, 30, 45 degrees). Discuss two equipment limitations of this choice and the modifications that would reduce each, with reference to the small-angle approximation. (4 marks)
A study measures the speed of waves on a string at five tensions $T$ : 5.0, 10.0, 15.0, 20.0, 25.0 N (uncertainty $\pm$ 0.2 N), with constant linear density $\mu = 1.50 \times 10^{-3}$ kg m $^{-1}$ . Wave speeds (m s $^{-1}$ ): 57.8, 81.0, 99.5, 115.2, 128.5. (a) Linearise $v = \sqrt{T/\mu}$ and calculate the gradient using the first and last points. (b) From the gradient, calculate the experimental value of $\mu$ . (c) Calculate the percent error from the accepted value and identify the dominant systematic source. (7 marks)
The student's evaluation writes: "The experiment was reproducible because we got similar results each time." Identify three weaknesses against QCAA top-band evaluation criteria, then rewrite a one-paragraph evaluation that addresses each weakness for the context of a projectile-range investigation. (5 marks)
An IA2 study investigates the relationship between gravitational acceleration and altitude using a pendulum at five altitudes around south-east Queensland (Brisbane CBD 30 m, Mount Coot-tha 290 m, Springbrook 950 m, Mount Tamborine 525 m, Sunshine Coast 5 m), getting $g$ values that vary by under 0.1 percent across the data set. (a) Calculate the expected percentage variation in $g$ from theory ( $g \propto 1/r^2$ with $r$ measured from the centre of the Earth, $R_E = 6.371 \times 10^{6}$ m) between altitudes 5 m and 950 m. (b) State whether the experimental result is consistent with theory and justify with reference to the data spread and the measurement uncertainty in a single-pendulum determination of $g$ (typically $\pm$ 0.5 percent). (c) Propose a modification to make the altitude variation detectable. (6 marks)
A student wishes to test whether the period of a vertical spring oscillator follows $T = 2 \pi \sqrt{m/k}$ . List five repeats needed to test reproducibility, two procedural modifications that would tighten the data, and one alternative measurement to verify $k$ independently. (5 marks)

Solutions

Q1: A hypothesis is a predicted relationship; a research question asks what specific relationship will be investigated under controlled conditions, with all variables specified to QCAA precision. Converted: "What is the relationship between the strength of a falling rare-earth magnet (measured as magnetic flux density at the leading face: 0.10, 0.20, 0.30, 0.50, 0.80 T, $\pm$ 0.01 T) and the peak induced EMF in a 500-turn coil of area 1.00 $\times 10^{-3}$ m $^2$ , dropping each magnet from a fixed height of 0.30 m through the coil?" This question rewards knowledge of IA2 research-question conventions (knowledge and analysis criterion).
The rewrite names IV (flux density) with five values and precision, fixes the coil and drop conditions, and ties to Faraday's law.
Q2: Limitation 1: stopwatch reaction time ( $\pm$ 0.20 s) is large compared to a single pendulum cycle ( $T \approx 2$ s), giving 10 percent random uncertainty per cycle. Modification: time 20 oscillations and divide by 20, reducing per-cycle uncertainty to 0.5 percent; better still, use a photogate timer ( $\pm$ 0.001 s). Limitation 2: at large amplitudes (30 and 45 degrees), the small-angle approximation $\sin\theta \approx \theta$ breaks down and the period deviates from $T = 2\pi \sqrt{L/g}$ by $T_{actual}/T_{small} = 1 + \theta^2/16 + \dots$ , giving a 1.0 percent correction at 45 degrees that the stopwatch cannot resolve against its own noise. Modification: restrict the amplitude range to 5 degrees and below, where the correction is under 0.04 percent; if larger amplitudes are required, fit the data to the higher-order correction explicitly. This question rewards judgement of equipment limitations (judgement criterion) and communication of modifications (communication criterion).
Stopwatch reaction time and small-angle breakdown at large amplitudes are the two limitations; photogate timing and amplitude restriction below 5 degrees are the modifications.
Q3: (a) Plot $v^2$ versus $T$ ; gradient $= 1/\mu$ . $v^2$ values: 3340.8, 6561.0, 9900.3, 13271.0, 16512.3 (m s $^{-1}$ ) $^2$ . Gradient $= (16512 - 3341)/(25.0 - 5.0) = 13171/20.0 = 658.6 \ \text{m}^2 \text{s}^{-2} \text{N}^{-1}$ . (b) $\mu = 1/658.6 = 1.518 \times 10^{-3} \ \text{kg m}^{-1}$ . (c) Percent error $= (1.518 - 1.50)/1.50 \times 100 = 1.2$ percent. Dominant systematic: the wave-speed measurement assumes the string is uniformly stretched along its full vibrating length, but tension can vary near the fixed ends (knots, clamping); also air resistance damping reduces the apparent speed of the leading edge of the disturbance. The 1.2 percent overshoot is consistent with a $-0.6$ percent bias in measured wave speed from end effects, or alternatively a 1.2 percent bias in the assumed linear density from variable string cross-section. This question rewards application of linearisation (application criterion) and judgement of systematic source (judgement criterion).
Gradient $658.6 \ \text{m}^2 \text{s}^{-2} \text{N}^{-1}$ gives $\mu = 1.52 \times 10^{-3} \ \text{kg m}^{-1}$ , 1.2 percent above accepted, with end-effect and cross-section variation as likely systematic sources.
Q4: Three weaknesses: (1) "Similar results" is not quantified; QCAA top-band requires RSD or standard deviation. (2) "Reproducible" is not the same as "accurate"; the statement says nothing about agreement with the accepted value. (3) No source-attribution and no modification proposed. Rewrite: "Across five trials at 30 degrees launch angle and $u = 6.0 \ \text{m s}^{-1}$ , the mean range was $R = 3.18 \pm 0.07$ m (RSD 2.2 percent), demonstrating acceptable precision. The theoretical range $R = u^2 \sin(2\theta)/g = 36.0 \times 0.866 / 9.80 = 3.18$ m matches the measured mean exactly to three significant figures, but the precision interval of $\pm$ 0.07 m corresponds to a $\pm$ 1.2 percent uncertainty in $u$ , the dominant random source; spring-launcher trigger asymmetry contributes most of this. The modification with highest impact would replace the spring launcher with a calibrated photogate-measured launch speed for each trial, reducing the per-trial uncertainty in $u$ to under 0.5 percent and tightening the predicted-versus-measured comparison below 1 percent." This question rewards judgement (judgement criterion) and communication of evaluation (communication criterion).
The original evaluation lacks quantification, accuracy-versus-precision distinction, and modification; the rewrite addresses all three with photogate launch-speed measurement.
Q5: (a) $g \propto 1/r^2$ with $r = R_E + h$ . At $h = 5$ m: $r_1 = 6\,371\,005$ m. At $h = 950$ m: $r_2 = 6\,371\,950$ m. Ratio $g_1/g_2 = (r_2/r_1)^2 = (1 + 945/6\,371\,005)^2 \approx 1 + 2 \times 1.48 \times 10^{-4} = 1.000297$ . Percentage variation $\approx 0.030$ percent. (b) The expected variation (0.030 percent) is far smaller than the single-pendulum measurement uncertainty ( $\pm$ 0.5 percent), so the experimental observation of variation under 0.1 percent is consistent with both the theoretical prediction and the no-variation null hypothesis - the experiment cannot distinguish between them. The result is therefore consistent with theory but not a useful test of it. (c) Modification: use a gravimeter (relative gravity meter with $\mu \text{Gal}$ precision, i.e., $1 \times 10^{-9}$ relative) rather than a pendulum; this would resolve the 0.030 percent altitude variation with margin to spare. Alternatively, choose a much larger altitude range (e.g., 0 m to 10,000 m via a high-altitude balloon experiment), where the variation grows to 0.31 percent and becomes resolvable by pendulum methods. This question rewards application (application criterion), judgement of measurement sensitivity (judgement criterion), and communication of modification (communication criterion).
The expected 0.030 percent altitude variation is far below the 0.5 percent pendulum uncertainty, making the local altitude experiment uninformative; a gravimeter or much greater altitude range is required.
Q6: Five repeats: (1) measure $T$ at each mass with five repeats per mass, giving 25 trials minimum (the QCAA expects five replicates per IV value, not five total). (2) Two procedural modifications: (i) time 20 oscillations per trial and divide by 20 to reduce timing uncertainty; (ii) hold the spring at fixed equilibrium-extension reference (the spring's hanging-mass equilibrium) before each trial to ensure consistent initial conditions. (3) Alternative measurement to verify $k$ : static deflection - hang each known mass on the spring and measure the equilibrium extension $x$ ; $k = mg/x$ . This gives an independent $k$ from a purely static measurement, which should agree with the dynamic $k$ from the $T^2$ -versus- $m$ gradient. Comparing the two values of $k$ tests whether non-linear or dissipative effects are present in the dynamic regime. This question rewards application (application criterion), knowledge of reproducibility design (knowledge and analysis criterion), and judgement of independent measurement (judgement criterion).
Five repeats per mass plus two procedural modifications (20-cycle timing, fixed initial conditions) and static deflection as an independent verification of $k$ .

Sources & how we know this

Physics General senior syllabus 2025 — QCAA