Physics and Mathematics
What this domain tests
Physics and mathematics checks mechanics, fluids, thermodynamics, electricity, waves and optics, plus algebra, functions, geometry, trigonometry, probability, and data handling. The exam favours direct application; write the formula, substitute SI units, and sanity-check the size of the answer.
Core rules
- Kinematics: v = u + at; s = ut + ½at²; v² = u² + 2as. Use signs consistently.
- Newton’s second law F = ma; weight is mg, not mass.
- Work and energy: W = Fd cosθ; kinetic energy ½mv²; power = energy/time.
- Ohm’s law V = IR; electrical power P = VI = I²R = V²/R.
- Probability of independent events multiplies; mutually exclusive events add.
- In trigonometry, check whether the calculator is in degrees or radians.
Worked example
A 6 Ω resistor carries a current of 2 A for 30 s. How much energy is dissipated? First find power: P = I²R = (2)² × 6 = 24 W. Energy = power × time = 24 × 30 = 720 J. Alternatively, V = IR = 12 V, then P = VI = 12 × 2 = 24 W, confirming the result. A common error is to compute 2 × 6 × 30 = 360 J by confusing current with voltage or forgetting to square the current.
Traps that cost marks
Convert centimetres to metres and minutes to seconds before substituting. Distinguish average from instantaneous speed. In optics, angles are measured from the normal. In probability, do not add probabilities of overlapping events without subtracting the overlap. In graphs, read the axis units and the requested gradient or area.