Which of the following best describes how the gravity model is calculated between two locations?

The gravity model in geography is utilized to predict the flow of people, goods, or information between two locations based on their populations and the distance that separates them. The fundamental principle behind the model is that larger places attract more interactions than smaller places, and this attraction decreases with increasing distance.

The correct formulation involves taking the product of the populations of the two locations, which represents the potential for interaction — larger populations typically generate more exchanges or flows. Dividing this product by the square of the distance accounts for the fact that as distance increases, the likelihood of interactions decreases significantly. The concept is similar to the gravitational force in physics, where the mass of the objects (populations) and the distance between them influence the gravitational pull. Therefore, the combination of these factors effectively models the spatial interaction between two areas.