I have applied the Loop Impact Method and the Newtonian Interpretative Framework to many models. Investigate these models to get a better understanding of the Newtonian approach to system dynamics models.
Limits To Growth Model
The model explains how growth is limited due to constraints on carrying capacity. It has one stock and at least two loops, the growth loop and the limits loop. I use an example of the growth of business structures with three loops
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A generic version of this model appears in the papers by Hayward and Roach (2017, 2019, 2022).
Diffusion Model
Diffusion models describe the process by which an entity spreads through a population. Examples include products, technology, ideas, a belief, or an infection.
This model appears in Hayward and Roach 2023.
SIR Model
The standard model of the spread of an infectious disease involves three stocks: susceptibles, infected and removed. Susceptibles become infected through contact with an infected person. Infected people eventually recover and are removed from the population dynamics.
The model has three stocks and three loops. However, there are only two independent stocks, determined by two equations, due to the conservation of the sum of the stocks.
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Versions of this model are studied in Hayward (2012), Hayward and Boswell (2014), Hayward and Roach (2024).