WACE Physics: how the ATAR Physics exam is built

How the WACE Physics exam is built

The Physics paper is not a multiple-choice paper. SCSA's design brief gives three written sections, and the middle one is the heaviest, so most of your marks come from multi-step problems with working shown.

The instructions ask for answers to three significant figures unless the question says otherwise, with units. The supervisor provides a Formulae and Data booklet, and you can use drawing templates, a compass, a protractor and up to three calculators that cannot store programs or text.

Unit 3 and Unit 4

• Unit 3, Gravity and relativity: projectile and circular motion, static equilibrium and torque, gravitational fields and orbits (including equatorial, polar and sun-synchronous orbits), electric and magnetic fields acting on charges, then special relativity and the evidence for it, and the consequences of general relativity such as gravitational lensing.
• Unit 4, Electromagnetism and modern physics: how electromagnetic waves are produced and travel, and how failures of older theories led to the quantum theory of light and matter.

Our Laws of Motion course covers the force and motion groundwork for Unit 3, and the Light and Energy course introduces photons for Unit 4.

Worked examples at ATAR level

Orbital speed

A satellite orbits Earth at a height of 600 km. Taking the radius of Earth as 6.38 × 10⁶ m, the orbit radius is 6.98 × 10⁶ m. With G = 6.67 × 10⁻¹¹ N m² kg⁻² and Earth's mass 5.97 × 10²⁴ kg (use the values in your booklet). Gravity provides the centripetal force, so:

The satellite's mass cancels, which is the point examiners usually want you to notice. The period is 2πr ÷ v ≈ 5560 s, about 93 minutes. Using the planet's radius instead of the orbit radius would give about 7.9 × 10³ m s⁻¹, five percent too high, and forgetting to add the height is a common lost mark on orbit questions.

Time dilation

A muon at rest lasts 3.0 μs. When it travels at 0.80c relative to a detector, the Lorentz factor is:

The detector measures a lifetime of 3.0 × 1.67 = 5.0 μs. Say who measures proper time (the muon's own clock) and who does not, since the explanation earns marks alongside the number.

Unit 3 builds on projectile motion, so test it in the Laws of Motion course, then press Mark:

School marks and how the ATAR forms

SCSA sets the school-based weightings for Year 12 Physics: a science inquiry portfolio 10%, tests 40% and examinations 50%. The portfolio is the collection of your practical work across the year, including analysis of data and uncertainties, and a small selection of its items is used to authenticate it. The course grade is A to E, with a school mark out of 100.

The school mark is statistically moderated against the exam marks at your school, then averaged with your exam mark to give the combined mark. TISC turns the combined marks from your ATAR courses into the ATAR.

Dates

Use the daily paper as a trial

A trial exam in Western Australia is set by your school, and there is no official one from SCSA. The free daily paper on the Year 12 Physics track is a short timed trial of 8 questions worth 25 to 35 marks, marked as you go. It is not a three-hour WACE paper.

• It fits: circular motion, gravitational fields and orbits, electric and magnetic fields, and electromagnetic induction all appear in its rotation.
• It does not fit: it also includes capacitors, simple harmonic motion, thermal physics and binding energy, which are not named in the WACE Year 12 syllabus. It gives no Formulae and Data booklet, so keep your own copy open for the constants.
• Year 11 practice: the Year 11 Physics paper is good for keeping kinematics and forces sharp, because Unit 3 builds on them straight away.

Exam answers

Answers and a worked mark scheme arrive with each daily paper once it has been marked. They are Uni-Sine's own and are not official SCSA answers, past paper solutions or a marking key.

Mistakes that cost marks

• Using the radius of the planet, or only the height above it, as the orbit radius, or forgetting to convert kilometres to metres.
• Stating a relativity result without saying whose time is proper time.
• Leaving a final answer with four or five significant figures when the instructions ask for three.
• Skipping the comprehension question in Section Three because the context looks unfamiliar. It is written so that the stimulus gives you what you need.

Read next

Australia · WACEWACE Physics formula sheet: the SCSA data bookletThe SCSA Physics ATAR Year 12 formulae and data booklet: all equations, physical data, what is missing, and worked orbit, field and photon examples.