Grade 11 Physical Sciences Past Papers 2021

Newton's Laws of Motion are the dominant mechanics topic in Grade 11 Physical Sciences Paper 1. Under the CAPS curriculum, learners extend their foundational knowledge to complex systems: blocks on inclined planes where weight must be resolved into components parallel and perpendicular to the surface, masses connected by strings over pulleys (Atwood machines), and stacked objects with friction acting between contact surfaces.

The distinction between static friction (which opposes impending motion and reaches a maximum just before the object moves) and kinetic friction (constant force opposing motion once sliding begins) is a recurring NSC Paper 1 examination point. Learners must draw accurate free-body diagrams for every object in the system, correctly label all forces including tension in the connecting string, and apply F_net = ma to each body separately to set up and solve simultaneous equations — a multi-step CAPS skill worth significant Paper 1 marks.

Geometrical Optics introduces Grade 11 learners to the behaviour of light at boundaries between media. Snell's Law (n₁ sin θ₁ = n₂ sin θ₂) governs refraction — the change in direction of a light ray as it passes from one medium to another of different optical density. The refractive index n = c / v quantifies how much a medium reduces the speed of light relative to its speed in a vacuum; a higher refractive index means a slower, more optically dense medium.

Total internal reflection occurs when light travels from a denser medium to a less dense medium at an angle of incidence exceeding the critical angle (where the refracted ray would emerge at exactly 90°). CAPS Paper 1 tests calculation of the critical angle using sin θ_c = n₂ / n₁ and requires learners to explain real-world applications — including optical fibres used in telecommunications and the internal brilliance of diamonds — in terms of total internal reflection.

Chemical Bonding and Intermolecular Forces form the backbone of Grade 11 CAPS Physical Sciences Paper 2. Learners classify chemical bonds as covalent (electron sharing), ionic (electron transfer), or metallic, and determine molecular polarity by combining bond polarity with molecular shape from VSEPR theory — a prerequisite for identifying the type of IMF present.

The three categories of IMFs — London dispersion forces (all molecules), dipole-dipole interactions (polar molecules), and hydrogen bonding (molecules containing N–H, O–H, or F–H bonds) — directly govern physical properties. Stronger IMFs produce higher boiling points and melting points, lower vapour pressure, and higher viscosity. NSC Paper 2 CAPS questions regularly ask learners to compare boiling points between substances such as water, ethanol, and propane, and to justify each comparison using the type and relative strength of the IMFs involved.

The Gas Laws chapter of Grade 11 CAPS Chemistry establishes the quantitative relationships between pressure, volume, temperature, and the amount of an ideal gas. Boyle's Law (p₁V₁ = p₂V₂ at constant temperature) and Charles's Law (V₁ / T₁ = V₂ / T₂ at constant pressure) are unified in the Ideal Gas Equation: pV = nRT, where R = 8.314 J·mol⁻¹·K⁻¹.

NSC Paper 2 CAPS questions require learners to convert temperature from Celsius to Kelvin (T = °C + 273), convert pressure to pascals and volume to cubic metres, substitute correctly into the chosen equation, and express the final answer in appropriate SI units. Standard conditions — STP (0 °C, 101.3 kPa) and SATP (25 °C, 100 kPa) — are defined in the NSC data booklet provided during the examination. Interpreting and sketching graphs of p vs V and V vs T are also examinable CAPS skills for Grade 11 Physical Sciences.