Cambridge Pre-U Physics (Principal Subject) Syllabus

Physics (Principal Subject) syllabus — full chapter and topic list

Expand any chapter to see its topics and sub-topics. This is the whole examinable outline for Physics (Principal Subject) in Cambridge Pre-U, not a summary of it.

1. 1

   Mechanics and Materials

   5 topics

   • Kinematics and Dynamics
     • Scalars, vectors and motion graphs
     • Newton's laws and free-body diagrams
     • Momentum, impulse and collisions
   • Forces in Equilibrium
     • Moments, couples and centre of mass
     • Conditions for static equilibrium
   • Work, Energy and Power
     • Energy conservation and efficiency
     • Power and its applications
   • Properties of Materials
     • Stress, strain and the Young modulus
     • Hooke's law and elastic strain energy
     • Brittle, ductile and plastic behaviour
   • Circular Motion
     • Angular velocity and centripetal acceleration
     • Centripetal force applications
2. 2

   Waves and Oscillations

   4 topics

   • Wave Properties
     • Transverse and longitudinal waves
     • Reflection, refraction and Snell's law
     • Total internal reflection and optical fibres
   • Superposition
     • Interference and Young's double-slit experiment
     • Diffraction gratings
     • Stationary waves and resonance
   • Simple Harmonic Motion
     • Defining equation and energy in SHM
     • Mass-spring and pendulum systems
     • Damping and forced oscillations
   • Sound and the Doppler Effect
     • Speed of sound and intensity
     • Doppler shift for moving sources
3. 3

   Electricity and Magnetism

   4 topics

   • Electric Circuits
     • Current, potential difference and resistance
     • Kirchhoff's laws and circuit analysis
     • Resistivity and internal resistance
   • Capacitance
     • Charge, capacitance and stored energy
     • Charging and discharging through a resistor
   • Electric Fields
     • Coulomb's law and field strength
     • Electric potential and equipotentials
   • Magnetic Fields
     • Force on a current-carrying conductor
     • Force on a moving charge
     • Electromagnetic induction and Faraday's law
4. 4

   Modern and Thermal Physics

   4 topics

   • Quantum Physics
     • The photoelectric effect
     • Wave-particle duality and de Broglie wavelength
     • Energy levels and line spectra
   • Nuclear Physics
     • Radioactive decay and half-life
     • Mass-energy equivalence, fission and fusion
     • Nuclear stability and binding energy
   • Thermal Physics
     • Temperature, internal energy and specific heat capacity
     • The ideal gas law and kinetic theory
     • First law of thermodynamics
   • Astrophysics and Cosmology
     • Stellar properties and Hertzsprung-Russell diagram
     • Hubble's law and the expanding universe

Physics (Principal Subject) flashcards for Cambridge Pre-U

22 of 65 cards from the Physics (Principal Subject) deck — real questions with worked answers.

1. State Newton's second law of motion in terms of momentum.

   The resultant force is equal to the rate of change of momentum: $$F = \frac{\Delta p}{\Delta t} = \frac{\Delta (mv)}{\Delta t}$$ For constant mass this reduces to $F = ma$.

2. Define impulse and state its relationship to momentum.

   Impulse is the product of force and the time for which it acts: $J = F\,\Delta t$. It equals the change in momentum: $$F\,\Delta t = \Delta p = m v - m u$$ Units: $\text{N s}$ (equivalently $\text{kg m s}^{-1}$).

3. Write the four equations of motion (suvat) for uniform acceleration.

   $$v = u + at,\quad s = ut + \tfrac{1}{2}at^{2},\quad v^{2} = u^{2} + 2as,\quad s = \frac{(u+v)}{2}\,t$$

4. Distinguish between an elastic and an inelastic collision.

   In both, momentum is conserved. In an elastic collision kinetic energy is also conserved; in an inelastic collision kinetic energy is not conserved (some is transferred to other forms). A perfectly inelastic collision is one where the objects stick together.

5. What is the condition for an object to be in equilibrium under coplanar forces?

   Two conditions: (1) the resultant force is zero (vector sum of forces $= 0$ in all directions); (2) the resultant torque about any point is zero ($\sum \tau = 0$). The object then has no linear or angular acceleration.

6. State the principle of moments.

   For a body in rotational equilibrium, the sum of the clockwise moments about any point equals the sum of the anticlockwise moments about that same point: $$\sum \tau_{\text{clockwise}} = \sum \tau_{\text{anticlockwise}}$$ where moment $\tau = F d$ (force $\times$ perpendicular distance).

7. What is a couple, and how is its torque calculated?

   A couple is a pair of equal, antiparallel forces whose lines of action do not coincide, producing rotation but no resultant force. Its torque (moment) is $$\tau = F d$$ where $F$ is one force and $d$ is the perpendicular separation between the two forces.

8. Define work done by a force and give the formula when the force is at an angle.

   Work is energy transferred when a force moves its point of application: $$W = F s \cos\theta$$ where $\theta$ is the angle between the force and the displacement. Unit: joule ($\text{J}$).

9. State the work-energy theorem.

   The net work done on an object equals its change in kinetic energy: $$W_{\text{net}} = \Delta E_k = \tfrac{1}{2}mv^{2} - \tfrac{1}{2}mu^{2}$$

10. Give the formulas for kinetic energy, gravitational potential energy, and power.

    $$E_k = \tfrac{1}{2}mv^{2},\qquad E_p = mg\Delta h,\qquad P = \frac{W}{t} = Fv$$ where $Fv$ is the power delivered by a force moving at velocity $v$.

11. Define efficiency and write its formula.

    Efficiency is the ratio of useful output energy (or power) to total input energy (or power): $$\eta = \frac{\text{useful energy output}}{\text{total energy input}} \times 100\%$$ It is always less than $100\%$ in real systems due to dissipation.

12. State Hooke's law and define the spring constant.

    For an elastic material below the limit of proportionality, extension is proportional to applied force: $$F = kx$$ where $k$ is the spring constant (force per unit extension, $\text{N m}^{-1}$) and $x$ is the extension.

13. Define the Young modulus and give its formula.

    The Young modulus is the ratio of tensile stress to tensile strain in the linear region: $$E = \frac{\sigma}{\varepsilon} = \frac{F/A}{x/L} = \frac{FL}{Ax}$$ Unit: pascal ($\text{Pa}$).

14. Define stress and strain.

    Stress is force per unit cross-sectional area: $\sigma = \dfrac{F}{A}$ (unit $\text{Pa}$). Strain is the fractional change in length: $\varepsilon = \dfrac{x}{L}$ (dimensionless).

15. What is the elastic strain energy stored in a stretched material obeying Hooke's law?

    The energy stored equals the area under the force-extension graph: $$E = \tfrac{1}{2}Fx = \tfrac{1}{2}kx^{2}$$

16. Distinguish between a ductile, a brittle, and a polymeric material's behaviour.

    Ductile materials (e.g. copper) undergo large plastic deformation and can be drawn into wires. Brittle materials (e.g. glass) show little plastic deformation and fracture soon after the elastic limit. Polymeric materials (e.g. rubber) show large extensions with non-linear, often hysteretic, behaviour.

17. Derive the formulas for angular speed and centripetal acceleration in circular motion.

    Angular speed: $\omega = \dfrac{2\pi}{T} = 2\pi f$ and $v = r\omega$. Centripetal acceleration is directed toward the centre: $$a = \frac{v^{2}}{r} = r\omega^{2}$$

18. Write the formula for the centripetal force required for circular motion.

    $$F = \frac{mv^{2}}{r} = m r \omega^{2}$$ directed toward the centre of the circle. It is a resultant force, not a separate force.

19. Define the radian and convert between radians and revolutions.

    One radian is the angle subtended at the centre of a circle by an arc equal in length to the radius. A full revolution is $2\pi$ radians ($360^{\circ}$), so $1\,\text{rev} = 2\pi\,\text{rad}$ and angle $\theta = \dfrac{s}{r}$.

20. List the defining quantities of a progressive wave: wavelength, frequency, period, and wave speed.

    Wavelength $\lambda$: distance between adjacent points in phase. Frequency $f$: oscillations per second ($\text{Hz}$). Period $T = \dfrac{1}{f}$. Wave speed: $$v = f\lambda$$

21. Distinguish between transverse and longitudinal waves, giving an example of each.

    In a transverse wave, oscillations are perpendicular to the direction of energy transfer (e.g. light/EM waves, waves on a string). In a longitudinal wave, oscillations are parallel to energy transfer, producing compressions and rarefactions (e.g. sound).

22. What is the intensity of a wave and how does it relate to amplitude and distance from a point source?

    Intensity is power per unit area: $I = \dfrac{P}{A}$. Intensity is proportional to amplitude squared, $I \propto A^{2}$, and for a point source obeys the inverse-square law $$I \propto \frac{1}{r^{2}}$$

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