Physics GCSE Paper 2 Summary

Overview

This lecture reviews all essential topics for AQA GCSE Physics Paper 2 (topics 5–7): Forces, Waves, Magnetism, and the Space topic (for Triple Science). Key definitions, formulas, concepts, and exam strategies are summarized.

Forces and Motion

• A force is a push or pull; can be contact (e.g., friction, tension) or non-contact (e.g., gravity, magnetism).
• Forces are represented by vectors (arrows show direction and magnitude).
• Resultant force is found by vector addition; use Pythagoras and trigonometry if at right angles.
• If forces are balanced (sum to zero), the object moves at constant velocity (Newton’s First Law).
• Scalars have only magnitude (e.g., mass), vectors have magnitude and direction (e.g., velocity, displacement).
• Weight = mass × gravitational field strength (W = m × g); g ≈ 9.8 N/kg (rounded to 10 N/kg sometimes).
• Work done = force × distance moved; for lifting, this is also gain in gravitational potential energy (GPE = m × g × h).
• Hooke’s Law: force = spring constant × extension (F = k × e); k in N/m; applies if deformation is elastic.
• Energy in a stretched spring: 0.5 × spring constant × extension² (E = ½ k e²).
• Moments: turning force = force × distance to pivot; balanced moments mean no rotation (Principle of Moments).
• Pressure = force ÷ area (P = F/A); units: pascals (Pa).
• Liquid pressure: P = height × density × g (P = hρg).
• Gas pressure results from particle collisions; increases with more particles, higher temperature, or smaller volume.

Kinematics and Dynamics

• Speed = distance/time; velocity = displacement/time; both in m/s, but velocity includes direction.
• Distance-time graph gradient = speed; velocity-time graph gradient = acceleration.
• Acceleration = change in velocity ÷ time (a = Δv/t).
• Area under velocity-time graph = distance traveled.
• Newton’s Laws:
  • First Law: no resultant force = constant velocity.
  • Second Law: resultant force = mass × acceleration (F = m × a).
  • Third Law: every action force has an equal and opposite reaction force.
• Stopping distance = thinking distance + braking distance; braking distance ∝ speed².
• Momentum = mass × velocity (p = m × v); conserved in collisions.
• Change in momentum / time = force; car safety features increase stopping time to reduce force.

Waves

• Waves transfer energy but not matter; oscillations move along.
• Longitudinal waves: oscillations parallel to direction (e.g., sound, seismic P waves).
• Transverse waves: oscillations perpendicular to direction (e.g., light, water waves, S waves).
• Wavelength: distance between peaks; frequency: waves per second (Hz); period: time for one wave (T = 1/f).
• Wave speed = frequency × wavelength (v = fλ).
• Reflection: angle of incidence = angle of reflection (measured from normal).
• Refraction: change in direction when wave changes speed between media.
• EM spectrum includes radio, micro, IR, visible, UV, X-rays, gamma; higher frequency = more energy.
• EM waves can ionize atoms (UV, X-rays, gamma), causing possible mutations.

Lenses and Light (Triple Only)

• Convex lenses converge rays; concave diverge.
• Magnification = image height ÷ object height.
• Real images can be projected; virtual cannot.
• Color: objects reflect some wavelengths, absorb others.
• Black body: perfect absorber/emitter of all wavelengths.

Magnetism and Electromagnetism

• Permanent magnets have aligned domains; North and South poles create magnetic fields (N→S).
• Magnetic field lines form closed loops.
• Induced magnets become magnetic in a field, lose magnetism when removed.
• Current in a wire creates a magnetic field; motor effect occurs in magnetic fields (Fleming’s left hand rule).
• Force on wire: F = B × I × L (B = magnetic flux density, I = current, L = length).
• Electric motors reverse current to keep turning (split ring commutator).
• Loudspeakers: motor effect turns current into sound.
• Generator/dynamo effect: moving wire in a magnetic field induces voltage (AC or DC).

Transformers and the National Grid

• Transformers use induction to change voltage; step-up increases voltage for transmission, step-down reduces it for use.
• Transformer equation: Np/Ns = Vp/Vs (turns ratio = voltage ratio).
• AC must be used in primary coil to induce current in secondary coil.
• Power (V × I) ideally conserved; high voltage used to reduce current and energy loss in cables.

Space (Triple Only)

• Solar system: Sun, 8 planets, asteroid belt, moons.
• Star lifecycle: nebula → main sequence → red giant/super red giant → white dwarf/black dwarf or supernova → neutron star/black hole.
• Satellites: natural (moons) or artificial; geostationary satellites maintain fixed position over Earth.
• Orbits involve centripetal force; velocity is tangential, force is toward center.
• Red-shift: stretched light from receding galaxies shows universe expansion (evidence for Big Bang).
• Cosmic Microwave Background Radiation (CMBR): leftover radiation from the Big Bang.

Key Terms & Definitions

• Force — push or pull on an object.
• Vector — quantity with magnitude and direction.
• Scalar — quantity with magnitude only.
• Resultant Force — single force combining all acting forces.
• Hooke’s Law — force needed to extend or compress a spring is proportional to extension.
• Moment — turning effect of a force.
• Pressure — force per unit area.
• Momentum — mass × velocity; conserved in collisions.
• Longitudinal Wave — oscillations parallel to wave direction.
• Transverse Wave — oscillations perpendicular to wave direction.
• Electromagnetic Spectrum — range of all EM wave frequencies.
• Magnetic Field — region of magnetic force around a magnet.
• Induced Magnet — material temporarily magnetized in a magnetic field.
• Transformers — devices for changing voltage via electromagnetic induction.
• Red-shift — increase in wavelength of light from objects moving away.

Action Items / Next Steps

• Review and memorize key equations and units listed above.
• Practice vector addition, using graphs, and applying Newton’s laws.
• For triple: focus extra revision on lenses, black bodies, and space topics.
• Work through sample GCSE questions on forces, waves, magnetism, and space.
• Prepare for practicals: Hooke’s law, measuring wave speed, motor effect, transformer models.