QCE Physics IA1 data test technique: The 2026 guide

Study guide15 min readUpdated 21 May 2026

Quick answer

QCE Physics IA1 Data Test is a 60-90 minute school-supervised response to unseen Unit 3 stimulus (graphs, tables, apparatus diagrams), testing calculation, reasoning and claim-and-justify with three significant figures, units throughout, and explicit show-working that allows method marks even when arithmetic slips; the assessment is worth 10 percent of the subject result and emphasises claim-evidence-reasoning under time pressure.

Jump to a section

What this guide is for
Format
Common stimulus types
Question types
Show working
Marking criteria
Time pressure techniques
Check your knowledge

What this guide is for

The QCE Physics IA1 data test is the first major Unit 3-4 assessment. This guide covers the format, marking criteria, common stimulus types, and the technique that produces strong responses under time pressure.

Format

Duration. 60-90 minutes (set by school, within QCAA guidelines).
Stimulus. Previously unseen data set (or sets) from Unit 3.
Worth. 10 percent of subject result.
When. Term 1 or early Term 2 of Year 12.

Common stimulus types

Motion graphs: Position-time, velocity-time, acceleration-time graphs. Slope and area carry physical meaning (velocity from slope of x-t; displacement from area under v-t).
Orbital data: Tables of planetary orbital periods and radii, requiring Kepler's third law to verify or extract a value.
Force-extension graphs: For springs (Hooke's law) or strings (tension).
Voltage-current graphs: Resistance from slope.
Banked-curve scenarios: Diagrams of cars on inclined curves.
Parallel-plate setups: Electron deflection in uniform electric field.
Velocity-selector or mass-spectrometer geometry: Crossed E and B fields, perpendicular forces.
Induction setups: Coil-and-magnet, transformer characteristics.

Question types

Calculation

"From the data in Table 1, calculate the centripetal force on the car on the banked curve."

Approach:

Identify the relevant physics (centripetal force on banked curve).
Write the formula symbolically.
Extract values from stimulus with correct units.
Substitute and calculate.
State answer with units and sig fig.

Reasoning

"Explain why the transformer becomes less efficient under load X."

Approach:

Identify the physics (transformer losses: copper, iron core, hysteresis).
State the principle.
Apply to the specific scenario in the stimulus.
Argue cause and effect.

Claim and justify

"Make a claim about the relationship between the variables in the data, and justify it."

Approach:

State a quantitative claim ("the period is proportional to the square root of length").
Justify with the data (gradient of linearised graph).
Justify with theory (the formula $T = 2\pi \sqrt{L/g}$ ).
Acknowledge limits (uncertainty, range of data).

Linearise T = 2π√(L/g) by plotting T² against L; the gradient is 4π²/g, so g follows directly from the slope under the IA1 analysis criterion.

Show working

QCAA awards method marks for correct identification of the principle and formula, even if the calculation slips. Always:

State the physics principle.
Write the formula.
Substitute values with units.
Calculate with appropriate sig fig.
State the answer with units.

The gradient of V against I is the conductor resistance R; combined with

P = I^{2}R

the same stimulus answers an extended claim about line-loss under the IA1 reasoning criterion.

Marking criteria

QCAA rewards:

Correct physics. Identifying the right principle.
Correct formula. Symbolic before substitution.
Show working. Method marks.
Significant figures and units.
Reasoning quality. Cause-effect links, theoretical justification.

Time pressure techniques

Read the stimulus carefully during perusal. Identify the physics each part requires.

Plan briefly: A 1-minute plan saves 5 minutes of confusion.
Don't get stuck: If a calculation seems wrong, move on; return at the end.
Reserve review time: 5 minutes at the end to check arithmetic, units, sig figs.

Common errors

Misreading the stimulus: Numbers can be misread; double-check.
Unit conversion forgotten: SI base units in calculations.
Sign convention: Vector quantities; positive direction must be consistent.
Wrong formula form: $P = VI = I^2R = V^2/R$ ; choose the right form for your knowns.
Calculator-style data analysis: Always interpret the numbers physically.

Check your knowledge

Six analytical questions on log-log graphs, residual analysis, and model validity in the IA1 Data Test style. ISMG criteria are signposted in the solutions. Three significant figures, units throughout, and explicit show-working.

A log-log plot of measured drag force $F_d$ versus speed $v$ gives a straight line of gradient $1.94 \pm 0.06$ . The student concludes $F_d \propto v^2$ . (a) Justify the conclusion with reference to the gradient value and uncertainty. (b) State, with calculation, whether the data are also consistent with $F_d \propto v$ . (c) Identify one further test of the $v^2$ model. (5 marks)
A student investigates the radial intensity $I$ of a point source at five distances $r$ . $r$ (m): 0.20, 0.40, 0.60, 0.80, 1.00; $I$ (W m $^{-2}$ ): 105, 26.5, 11.5, 6.6, 4.2. (a) Linearise as $\log I$ versus $\log r$ and calculate the gradient. (b) State what the gradient implies about the relationship between $I$ and $r$ . (c) Calculate the percent deviation of each data point from the best-fit line and identify any outlier. (7 marks)
The student records the residuals (measured minus predicted, in N) from a Hooke's-law fit ( $F = k x$ ) at six extension values: 0.10 m: $+0.05$ N; 0.20 m: $-0.02$ N; 0.30 m: $-0.04$ N; 0.40 m: $-0.01$ N; 0.50 m: $+0.10$ N; 0.60 m: $+0.25$ N. (a) Plot conceptually what the residuals show as a function of extension. (b) State whether the residuals are consistent with Hooke's law over the full range and justify. (c) Propose a model for the apparent non-linearity at large extension. (5 marks)
A current-versus-voltage data set across a filament lamp shows $I$ (A) at $V$ (V): 0.5, 0.04; 1.0, 0.07; 2.0, 0.12; 4.0, 0.18; 8.0, 0.26; 12.0, 0.32. (a) State whether Ohm's law applies, with justification from the data. (b) Calculate the resistance $V/I$ at $V = 1.0$ V and at $V = 12.0$ V; explain the difference in physical terms. (c) Propose a linearisation that would test a power-law relationship $V \propto I^n$ and state how to extract $n$ . (6 marks)
A Hall-effect experiment relates Hall voltage $V_H$ to current $I$ at fixed $B$ in a thin semiconductor strip. Data: $I$ (mA): 5, 10, 20, 40, 60; $V_H$ (mV): 1.05, 2.12, 4.18, 8.31, 12.48. (a) Calculate the gradient using the first and last points. (b) State, with calculation, whether the data support the proportionality $V_H \propto I$ predicted by theory (use the middle three points to test consistency with the gradient). (c) Identify the dominant uncertainty source in this measurement. (6 marks)
A student measures the centripetal force $F_c$ on a rotating mass $m = 0.250$ kg at radius $r = 0.500$ m for five angular speeds. $\omega$ (rad s $^{-1}$ ): 2.00, 4.00, 6.00, 8.00, 10.00; $F_c$ (N): 0.51, 2.05, 4.55, 8.10, 12.85. (a) Verify the relationship $F_c = m r \omega^2$ by tabulating $F_c / \omega^2$ . (b) Calculate the percent error from the theoretical value $m r = 0.125$ kg m. (c) Identify the dominant source of uncertainty and propose a procedural modification to address it. (6 marks)

Solutions

Q1: (a) The gradient $1.94 \pm 0.06$ on a log-log plot of $F$ versus $v$ means $F \propto v^{1.94}$ ; the value 2.00 lies within the uncertainty interval (1.88 to 2.00), so the data are consistent with $F_d \propto v^2$ and the conclusion is justified. (b) The exponent 1.94 differs from 1.00 by 0.94, which is 15.7 standard deviations of the gradient uncertainty - not consistent with $F_d \propto v$ . (c) Further test: collect data at a wider speed range (e.g., 0.1 m s $^{-1}$ to 10 m s $^{-1}$ ) to check whether the gradient remains 2 at low speeds (where viscous drag $F \propto v$ may dominate) and whether a transition is observed; alternatively, compare measured drag coefficient $C_d = 2 F_d / (\rho A v^2)$ across the data set and check whether it is a constant. This question rewards application of log-log analysis (application criterion) and judgement of model fit (judgement criterion).
The gradient $1.94 \pm 0.06$ supports $F_d \propto v^2$ and rules out $F_d \propto v$ at 15.7 sigma; wider-range data is the recommended further test.
Q2: (a) Table: $\log r$ (m): $-0.699, -0.398, -0.222, -0.097, 0$ ; $\log I$ (W m $^{-2}$ ): 2.021, 1.423, 1.061, 0.820, 0.623. Gradient $= (0.623 - 2.021) / (0 - (-0.699)) = -1.398 / 0.699 = -2.00$ . (b) Gradient $-2.00$ on a log-log plot of $I$ versus $r$ confirms the inverse-square law: $I \propto r^{-2}$ . (c) Percent deviations from the line of best fit (using $I = I_0 r^{-2}$ with $I_0 =$ value at $r = 1.00$ m, so $I_{pred} = 4.20 / r^2$ ): predicted (W m $^{-2}$ ): 105.0, 26.25, 11.67, 6.56, 4.20; measured 105, 26.5, 11.5, 6.6, 4.2; deviations: 0 percent, 1.0 percent, $-1.4$ percent, 0.6 percent, 0 percent. No outliers; all points within 1.5 percent of the inverse-square line. This question rewards application of log-log linearisation (application criterion) and judgement of model validity (judgement criterion).
Gradient $-2.00$ confirms inverse-square law within 1.5 percent at every point, no outliers.
Q3: (a) Plot of residual $r_F$ versus extension $x$ shows a roughly horizontal trend through zero for $x = 0.10$ to 0.40 m, then a sharp rise to $+0.10$ N at $x = 0.50$ m and $+0.25$ N at $x = 0.60$ m. (b) Residuals are consistent with Hooke's law only for $x \leq 0.40$ m; at larger extensions the residuals are positive and growing, indicating the spring is stiffening beyond the linear regime. (c) Proposed model: the spring exhibits non-linear stiffening at large extension, well described by $F = k x + \alpha x^3$ where the cubic term accounts for finite coil-spacing effects as the spring nears its maximum stretch. This question rewards application of residual analysis (application and knowledge and analysis criteria) and judgement of model validity (judgement criterion).
Residuals are flat for $x \leq 0.40$ m then grow rapidly, suggesting Hooke's law fails above 0.40 m and a cubic stiffening term is appropriate.
Q4: (a) Ohm's law states $V/I$ is constant; here $V/I$ at the six voltages: 12.5, 14.3, 16.7, 22.2, 30.8, 37.5 ohms. Resistance triples (12.5 to 37.5 ohms) as voltage rises - Ohm's law does not apply. (b) At $V = 1.0$ V: $R = 1.0/0.07 = 14.3$ ohms (filament cool). At $V = 12.0$ V: $R = 12.0/0.32 = 37.5$ ohms (filament hot). The filament heats up as current increases; tungsten resistance increases with temperature (positive temperature coefficient), so the cool-filament resistance is lower than the hot-filament resistance. (c) Linearise as $\log V$ versus $\log I$ : if $V \propto I^n$ then $\log V = n \log I + \text{const}$ , and the gradient gives $n$ . Using first and last points: $\log V$ : $-0.301, 1.079$ ; $\log I$ : $-1.398, -0.495$ . $n = (1.079 - (-0.301)) / (-0.495 - (-1.398)) = 1.380/0.903 = 1.53$ . So $V \propto I^{1.5}$ approximately, consistent with a power-law heating model. This question rewards application of Ohm's-law analysis (application criterion), knowledge of conductor physics (knowledge and analysis criterion), and judgement of model selection (judgement criterion).
Ohm's law fails; $R$ triples from 12.5 to 37.5 ohms across the range as the filament heats, and $V \propto I^{1.5}$ approximately.
Q5: (a) Gradient $= (12.48 - 1.05)/(60 - 5) = 11.43/55 = 0.208 \ \text{V A}^{-1}$ . (b) Test $V_H/I$ at intermediate points: $V_H/I$ (V A $^{-1}$ ): 0.210, 0.212, 0.209, 0.208, 0.208. All within about 2 percent of the first-to-last gradient (0.208), so the linear proportionality is confirmed. (c) Dominant uncertainty: small offset voltage from misalignment of the Hall-probe contacts, which adds a constant additive offset to every reading; this would show as a non-zero intercept on a $V_H$ versus $I$ plot. Modification: zero the Hall voltage at $I = 0$ before taking measurements, and use a four-point probe configuration to cancel contact-misalignment offsets. This question rewards application of linearity testing (application criterion) and judgement of an instrument-specific systematic error (judgement criterion).
$V_H/I$ is $0.208 \ \text{V A}^{-1}$ to within about 2 percent across the data set; Hall-probe contact-offset is the dominant uncertainty.
Q6: (a) $\omega^2$ : 4.00, 16.0, 36.0, 64.0, 100.0; $F_c/\omega^2$ : 0.1275, 0.1281, 0.1264, 0.1266, 0.1285. Values cluster around 0.127 kg m, confirming $F_c \propto \omega^2$ . (b) Mean $F_c/\omega^2 = 0.1274$ kg m. Theory $m r = 0.250 \times 0.500 = 0.125$ kg m. Percent error $= (0.1274 - 0.125)/0.125 \times 100 = 1.92$ percent. (c) Dominant source: the rotating-mass orbit is rarely perfectly horizontal because the string sags slightly under tension, so the effective radius is less than the measured straight-line string length. This biases the experimental $m r$ value upward by a few percent, consistent with the 1.92 percent overshoot. Modification: replace the string with a rigid rod, or use a stroboscopic photograph to measure the actual orbital radius directly under rotation. This question rewards application of circular-motion analysis (application criterion), judgement of systematic source (judgement criterion), and communication of modification (communication criterion).
$F_c/\omega^2 = 0.127$ kg m, 1.9 percent above theoretical $m r = 0.125$ kg m; string sag is the dominant systematic, rigid-rod is the targeted modification.

Sources & how we know this

Physics General senior syllabus 2025 — QCAA