Question 1
A student astronomy club measures the orbital radius r and period T of four moons of a distant planet. The graph shows T² against r³. What is the planet's mass? Use G = 6.67 × 10⁻¹¹ N m² kg⁻².
WACE Physics comprehension and data analysis
Section Three has two questions worth 20% together: one asks you to apply physics to an unfamiliar context, the other to analyse experimental data.
| Section Three | Two questions, 20% of the examination, about 40 minutes |
|---|---|
| Comprehension | Physics applied to a passage, possibly on an unfamiliar context |
| Data analysis | Graphs, gradients, intercepts and uncertainty from experimental data |
Analysing data
- Choose what to plot so the relationship is a straight line, then relate the gradient and intercept to physical quantities.
- Use uncertainty bars, find the gradient from a line of best fit, and quote absolute and percentage uncertainties.
- Separate random from systematic errors and say how each one affects the result.
Reading an unfamiliar context
Find the physics you already know inside the passage: the forces, fields or energy changes it describes. Then answer with that physics, using the passage's numbers.
Try 2 questions
Question 2
A student lights a metal with several frequencies and finds the maximum kinetic energy of the photoelectrons for each. The graph shows her line of best fit: it meets the frequency axis at 4.40 × 10¹⁴ Hz and passes through 2.06 eV at 9.40 × 10¹⁴ Hz. What value of Planck's constant does the graph give? (1 eV = 1.60 × 10⁻¹⁹ J)
Next step
Questions people ask
Do I need to know the context before the exam?
No. The comprehension question can come from an unfamiliar context; it tests the physics of Units 3 and 4 applied to it.