GTLE Subject Specialism Physics cheat sheet

Newton's second law: net force equals mass times acceleration (F = ma); acceleration is always in the direction of the net force, not necessarily the direction of motion.

Kinematic equations apply only for constant acceleration: v = u + at, s = ut + ½at², v² = u² + 2as, s = ½(u + v)t.

Projectile motion separates into independent horizontal (constant velocity) and vertical (constant acceleration g) components; time of flight is set by vertical motion alone.

Momentum p = mv is conserved in any collision with no external net impulse; kinetic energy is conserved only in elastic collisions.

Circular motion requires centripetal acceleration a = v²/r directed toward the centre; the centripetal force is provided by friction, tension, gravity, or a normal force.

Work done W = Fs cosθ; the work-energy theorem states net work equals change in kinetic energy.

Hooke's law F = kx holds within the elastic limit; elastic potential energy stored is ½kx².

Conditions for static equilibrium: net force zero and net torque zero about any chosen pivot point.

Wave equation v = fλ; frequency is fixed by the source and does not change on refraction, while speed and wavelength do.

Transverse waves oscillate perpendicular to propagation; longitudinal waves (sound) oscillate parallel to propagation and cannot be polarised.

Snell's law: n₁ sinθ₁ = n₂ sinθ₂; refractive index n = c/v. Total internal reflection occurs when the angle exceeds the critical angle sinθc = n₂/n₁.

For a converging lens or concave mirror, 1/f = 1/u + 1/v with real-is-positive sign convention; magnification m = v/u.

Diffraction is greatest when the gap or obstacle is comparable to the wavelength; double-slit maxima occur at d sinθ = nλ.

Sound intensity level in decibels: β = 10 log₁₀(I/I₀), with I₀ = 1 × 10⁻¹² W m⁻².

The Doppler effect raises observed frequency when source and observer approach and lowers it when they recede.

Superposition gives constructive interference at path difference nλ and destructive interference at (n + ½)λ.

Ohm's law V = IR applies to ohmic conductors at constant temperature; resistance R = ρL/A shows dependence on length, area, and material.

Series: same current, voltages add, R_total = R₁ + R₂ + …; parallel: same voltage, currents add, 1/R_total = 1/R₁ + 1/R₂ + …

Electrical power P = VI = I²R = V²/R; energy transferred is power × time.

Kirchhoff's laws: current into a junction equals current out (charge conservation); sum of emfs equals sum of potential drops around a loop (energy conservation).

Coulomb's law F = kQ₁Q₂/r²; electric field E = F/q, and field lines point from positive to negative charge.

Magnetic force on a current-carrying wire F = BIL sinθ; on a moving charge F = qvB sinθ, directed by Fleming's left-hand rule.

Electromagnetic induction: induced emf equals the rate of change of magnetic flux linkage (Faraday); Lenz's law gives the induced current a direction opposing the change.

A transformer obeys V_s/V_p = N_s/N_p; an ideal transformer conserves power, so V_pI_p = V_sI_s.

Specific heat capacity: Q = mcΔT; specific latent heat: Q = mL applies at constant temperature during a phase change.

Ideal gas law pV = nRT; combining with kinetic theory gives mean kinetic energy per molecule = (3/2)kT.

Pressure of a gas arises from molecular collisions with container walls; it rises with temperature because mean molecular speed and collision rate increase.

Internal energy of an ideal gas depends only on temperature, since there are no intermolecular potential energy terms.

First law of thermodynamics: ΔU = Q − W, where W is work done by the gas; sign conventions must be stated explicitly.

Absolute zero (0 K = −273.15 °C) is the temperature at which molecular kinetic energy is minimal; Kelvin temperature must be used in gas-law calculations.

Thermal conduction rate through a slab: P = kAΔT/L; convection transfers heat by bulk fluid movement and radiation needs no medium.

Efficiency of a heat engine = useful work output / heat input; Carnot efficiency = 1 − T_cold/T_hot in kelvin.

Photoelectric effect: photon energy E = hf; maximum kinetic energy of emitted electrons = hf − work function φ.

Threshold frequency f₀ = φ/h; below it no emission occurs regardless of intensity, which supports the photon model.

de Broglie wavelength λ = h/p = h/(mv); electron diffraction confirms wave behaviour of particles.

Atomic energy levels: photon emitted or absorbed has energy hf equal to the energy difference between levels.

Nuclear notation ᴬZX: A is nucleon number, Z is proton number; isotopes share Z but differ in A.

Alpha decay reduces A by 4 and Z by 2; beta-minus decay leaves A unchanged and raises Z by 1; gamma emission changes neither.

Half-life: after n half-lives the remaining fraction is (½)ⁿ; activity A = λN and decays exponentially.

Mass defect converts to binding energy via E = mc²; binding energy per nucleon peaks near iron-56, so fusion releases energy for light nuclei and fission for heavy ones.

Precision is the smallest scale division of an instrument; uncertainty of a single reading is typically ± half the smallest division.

For analogue scales, quote uncertainty as ± half the least count; for digital meters, use ± the last digit.

Percentage uncertainty = (absolute uncertainty / measured value) × 100; uncertainties add for sums and differences, and percentage uncertainties add for products and quotients.

Random errors scatter readings about a true value and are reduced by averaging repeats; systematic errors shift all readings the same way and require calibration or zeroing.

A vernier calliper reads to 0.1 mm and a micrometer to 0.01 mm; check for zero error before use.

Plot graphs with the independent variable on the x-axis; a straight line through the origin supports proportionality, and gradient units follow from axis units.

Electrical safety: use low-voltage supplies, check insulation, keep water away from circuits, and switch off before rewiring.

Optics safety: never look directly at a laser beam or its specular reflection; use class-appropriate lasers and beam stops.

A scheme of work sequences topics so prerequisites precede dependents: kinematics before dynamics, circuits before electromagnetism, waves before optics.

Learning objectives should be written as observable outcomes using verbs such as calculate, describe, explain, or predict, matched to the assessment.

Practical work should be planned with a clear aim, variables identified, and a stated method for controlling extraneous variables.

Spiral sequencing revisits core ideas (energy, forces, waves) at increasing depth across year groups rather than teaching them once.

Mathematical demand should be staged: substitute into a given equation, then rearrange, then combine two equations, then derive.

Formative checks (mini whiteboards, hinge questions, exit tickets) should be planned at points where misconceptions are likely to surface.

Cross-topic links worth planning explicitly: energy conservation across mechanics and electricity; waves linking sound, light, and quantum behaviour.

Differentiation by scaffolding (worked examples, partially completed solutions, structured writing frames) supports access without lowering the assessed objective.

Diagnostic assessment should target known misconceptions, e.g. 'force is needed to keep an object moving' or 'current is used up in a bulb'.

Marking of calculations should credit the equation, substitution, and answer with unit separately, so method marks survive an arithmetic slip.

Command words matter: 'state' needs a brief answer, 'describe' needs what happens, 'explain' needs a causal mechanism.

Common misconception: heavier objects fall faster - in the absence of air resistance all objects accelerate at g.

Common misconception: current is shared equally in a parallel circuit - voltage is equal, current divides inversely with resistance.

Common misconception: sound travels through a vacuum, or light needs a medium - sound needs a medium, light does not.

Common misconception: temperature is the same as heat, and 'suction' or 'cold' pulls heat - heat flows from hot to cold spontaneously.

Feedback is most effective when specific, timely, and followed by student action (redrafting, correcting, or re-attempting a similar item).

Gradient of a straight-line graph equals the constant rate of change; area under the line equals the quantity obtained by multiplying the axes.

On a displacement-time graph, gradient is velocity; on a velocity-time graph, gradient is acceleration and area is displacement.

On a current-voltage graph, the gradient of the tangent at a point gives 1/R for a non-ohmic component.

Rearranging formulas: perform the same operation on both sides; check by substituting a known value after rearrangement.

Significant figures: the answer should carry the same number of significant figures as the least precise input, and units must be consistent (convert mm to m, g to kg).

Proportionality requires a straight line through the origin; a straight line with a non-zero intercept indicates a systematic offset.

Logarithmic and exponential relations: plotting log y against x linearises y = abˣ, with gradient log b.

Vector addition by scale drawing or components: resolve into perpendicular components, add components separately, then recombine with Pythagoras and trigonometry.

A displacement-distance graph shows wavelength directly; a displacement-time graph at a fixed point shows period directly.

Wave speed from a ripple tank: v = fλ measured by counting fringes over a known distance and timing a fixed number of oscillations.

Sound speed by resonance tube: v = 2f(L₂ − L₁) using successive resonance lengths to eliminate end correction.

Snell's law verification: plot sin i against sin r; gradient gives n₂/n₁ if light passes from medium 1 into medium 2.

Lens focal length by distant object or by u-v plot: 1/v against 1/u has intercepts at 1/f.

Total internal reflection is only possible when travelling from a denser to a less dense medium; check n₁ > n₂ before applying the critical-angle formula.

Diffraction grating: d sinθ = nλ with d = 1/(lines per metre); larger wavelength produces larger angular separation.

Ray diagrams for a converging lens: a ray parallel to the axis passes through the focal point; a ray through the centre continues undeviated.