Cambridge Syllabus Notes

9 Modelling

What is Modelling?

Think of modelling as building a LEGO set that represents a real‑world system. You choose the bricks (variables), decide how they fit together (relationships), and then play with the set to see what happens. In IT, we use simulations to test ideas without risking real resources.

Represents complex systems in a simplified form.
Allows experimentation and prediction.
Helps in decision‑making and risk assessment.

Key Concepts

Variables – the elements that can change (e.g., temperature, wind speed).
Parameters – fixed values that define the model (e.g., gravity = 9.81 m/s²).
Equations – mathematical relationships (e.g., $S = \frac{1}{2} a t^2$).
Assumptions – simplifications that make the model manageable.

Disaster Planning Simulation 🚒

Imagine you’re the chief of a city’s emergency services. You need to predict how a fire will spread through a neighbourhood to allocate resources effectively.

Define the scenario – e.g., a 3‑storey apartment block on a windy day.
Identify variables – wind speed, building materials, fire suppression systems.
Set parameters – average fire spread rate = 0.5 m/s.
Run the simulation using a tool (e.g., MATLAB, Python).
Analyse the output – time to reach each floor, required fire trucks.

Scenario	Key Variables	Outcome
Windy day, 3‑storey block	Wind speed, material flammability	Fire spreads 30 m in 2 min; 3 fire trucks needed
Calm day, 5‑storey block	Wind speed, sprinkler coverage	Fire contained after 5 min; 1 fire truck needed

Pilot Training Simulation 🛩️

Pilots use flight simulators to practise emergency procedures without risking an aircraft. The simulator models physics, weather, and aircraft systems.

Choose the flight scenario – e.g., engine failure at 10,000 ft.
Set environmental conditions – turbulence, visibility.
Define pilot actions – throttle, flaps, communication.
Run the simulation and record performance metrics (e.g., time to stabilize).
Review the flight log and adjust training.

Scenario	Key Variables	Outcome
Engine failure at 10,000 ft	Altitude, wind shear, fuel load	Successful glide to nearest airport in 4 min
Mid‑air collision avoidance	Air traffic data, autopilot settings	Safe separation achieved in 30 s

Exam Tips

Remember:

Define all variables clearly before building a model.
Show the equations you use – write them in LaTeX format if required.
Explain any assumptions you make.
Use a table to summarise scenarios and outcomes – it looks tidy and is easy to read.
Include a short reflection on how the simulation could be improved.

Use simulations (disaster planning, pilot training)