SPC Physics — A Speed Guide to Gold

The goal is simple: gold, and a ticket to the British Physics Olympiad (BPHO). Target around 35 points, leaving margin for error. This guide is built from a question-by-question breakdown of 18 past papers (2007–2025, excluding 2021) — 226 questions, each recategorised by the physics it actually tests.

Two rules to burn in first. MCQs carry no penalty for wrong answers — never leave one blank; eliminate impossible options and guess. Long-answer questions award marks step by step: write every equation, every substitution, name the principle — method marks survive a wrong final number; a skipped part earns zero.

The guaranteed marks — fixed topic, fixed method

These 55 questions (24% of the paper) have stable formats. Drill them to automaticity.

Fermi estimation (22 questions — the single biggest topic)

How long to walk to the moon? How long before a dog unrolls a toilet paper roll? The method never varies: bracket the order of magnitude, match the nearest option. Average difficulty only d2.2 yet almost nobody drills it systematically — that is where the gap opens. This topic has been growing: 2024 alone had five estimation questions.

Dimensional analysis and unit conversion (11 questions)

Even cheaper than estimation — average d2.0. Derive a formula from units, convert between SI and CGS, handle prefixes. Memorise the method and these become ten-second items.

Conservation of mechanical energy (13 questions)

½mv² + mgh = const; rolling objects share energy with rotation. Early papers placed these in MCQ as giveaways; recent years have pushed them into long-answer at d4–d5, coupled with geometric constraints and elastic potential energy. Do not just know the formula — practise chaining it with boundary conditions.

Projectile and vertical motion (7 questions)

T = 2v₀/g, h = ½gt², range formula. The most common trap: computing only the upward half of flight time, or assuming flight time scales with v₀² rather than linearly.

High-frequency, moderate depth (54% of the paper combined with above)

Kinematics — pursuit and relative motion

The classic "fly between two approaching walls" — do not calculate each bounce leg; compute how long until the walls meet, multiply by fly speed. Near-certain long-answer appearance in recent papers.

Forces and equilibrium

Free-body diagram, Newton's laws on slopes. One perennial trap: constant velocity means zero net force, regardless of the value of that velocity.

Circuits — the anchor topic

32 questions; every one of the last eight papers included a long-answer circuit problem. Series/parallel resistance, meter loading, non-linear elements (lamp filament, LED, thermistor), resistivity and geometry, charged particle acceleration. Typical difficulty d4. If you want a high score, there is no route around circuits.

Buoyancy and fluid flow

Archimedes, continuity equation A₁v₁ = A₂v₂, hydrostatic pressure. Classic trap: ice melting does not change water level, but a stone thrown from a boat into the water does lower it — ice displaces by mass, stone by volume.

Believe it or not: in 18 papers and 226 questions, true simple harmonic motion appears exactly once (2007). Springs and pendulums show up frequently — but the SPC tests them via dimensions, equilibrium or energy, not SHM formulae. One pass is enough.

Low priority — do last

• Thermal physics — 9 questions total, none in the most recent 8 papers. Lowest return on study time.
• Modern physics — 15 questions; formulae (E = hf, A = λN) cover most of it, but recent long-answer appearances are hard.
• Gravity and orbital mechanics — only 4 questions in SPC, mostly astronomical geometry. Reserve for BPHO proper where it dominates.
• Graphical analysis and experiment — scarce in SPC but d4–d5 when it appears; strategic skip if time is short.