OCR A Level Physics B (Advancing Physics)
OCR A Level Physics B Module 5: Rise and Fall of the Clockwork Universe Exam Questions
Free OCR A Level Physics B exam questions for Module 5: Rise and Fall of the Clockwork Universe, with a mark scheme for every pack. Covers exponential models, capacitor discharge, radioactive decay, simple harmonic motion, gravity and orbits, ideal gases and the Boltzmann factor.
Module 5: Rise and Fall of the Clockwork Universe exam questions
1 question pack of real past exam questions, each with its mark scheme. Do not stop after a few: answer as many as you can without notes, then mark every answer with the mark scheme. The more questions you do, the more quickly you will spot how examiners ask about each idea.
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About OCR A Level Physics B Module 5: Rise and Fall of the Clockwork Universe
Module 5 of OCR A Level Physics B (Advancing Physics), Rise and Fall of the Clockwork Universe, explores how mathematical models describe the physical world and where Newtonian ideas reach their limits. It covers exponential change in capacitors and radioactive decay, iterative and computational models, simple harmonic motion and resonance, gravitational fields and orbits, the kinetic theory of gases, and the Boltzmann factor for thermal activation. The title reflects how a predictable, mechanical view of the universe gives way to statistical thinking. Examiners test exponential decay equations and logarithmic graphs, SHM, orbital calculations, ideal gas problems and using the Boltzmann factor.
What you need to know
- Creating models Exponential decay where rate of change is proportional to the amount, such as dQ/dt = -Q/RC and dN/dt = -lambda N, solved by iteration and by Q = Q0 e^(-t/RC); time constant and half-life; log-linear graphs.
- Oscillations SHM with acceleration proportional to and opposite to displacement, period of mass-spring and pendulum systems, energy in SHM, damping and resonance.
- Out into space Newton's law of gravitation, gravitational field and potential, energy in orbits, and circular orbits where gravitational force provides the centripetal force.
- Matter: very simple The ideal gas equations pV = nRT and pV = NkT, the kinetic theory model and pV = 1/3 N m c^2, and the link between mean kinetic energy and temperature.
- Matter: hot or cold The Boltzmann factor e^(-E/kT) as the ratio of particles with enough energy for a process, explaining evaporation, reaction rates and conduction in semiconductors; specific heat capacity and internal energy.
Common mistakes in Module 5: Rise and Fall of the Clockwork Universe
- Plotting Q against t to find the time constant from a straight line. Plot ln Q against t: the gradient is -1/RC.
- Using too large a time step in an iterative model. Larger steps reduce accuracy; smaller steps give results closer to the exact exponential.
- Forgetting the Boltzmann factor uses energy per particle. E must be in joules per particle, with k = 1.38 x 10^-23 J K-1.
- Using Celsius temperatures in gas law calculations. Always convert to kelvin.
- Writing that orbital speed depends on the satellite's mass. Orbital speed depends only on the central mass and orbital radius, since the satellite's mass cancels.
Try three Module 5: Rise and Fall of the Clockwork Universe exam-style questions
1. Calculate the Boltzmann factor for a process with activation energy 0.50 eV at 300 K. (3 marks)
Show the mark scheme answer
E = 0.50 x 1.60 x 10^-19 = 8.0 x 10^-20 J; kT = 1.38 x 10^-23 x 300 = 4.14 x 10^-21 J; e^(-E/kT) = e^(-19.3) = 4.1 x 10^-9.
2. A capacitor discharges with a time constant of 5.0 s. Calculate the fraction of charge remaining after 10 s. (2 marks)
Show the mark scheme answer
Q / Q0 = e^(-10 / 5.0) = e^-2; = 0.14.
3. Explain why the rate of an evaporation process increases rapidly with temperature. (3 marks)
Show the mark scheme answer
Only particles with energy above a threshold can escape; the fraction with enough energy is given by the Boltzmann factor; a small rise in T greatly increases e^(-E/kT) because it is exponential.
Module 5: Rise and Fall of the Clockwork Universe FAQs
What does OCR A Level Physics B Module 5: Rise and Fall of the Clockwork Universe cover?
Creating models (exponential change and oscillations), gravity and orbits, kinetic theory of gases and the Boltzmann factor.
Why is it called the clockwork universe?
It starts with predictable Newtonian models of motion and gravity, then shows why statistical ideas such as the Boltzmann factor are needed for large numbers of particles.
Which graph skills matter most for this module?
Using logarithmic graphs to test for exponential relationships, and interpreting SHM displacement, velocity and acceleration graphs.
