Gravity Model – AP Human Geography | ShowMeClass

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Gravity Model

AP Human Geography · Unit 2: Population & Migration

Learning Objectives

Understand the gravity model of spatial interaction

Explain how population and distance affect interaction

Calculate interaction strength between two cities

Apply the model to migration, trade, and commuting

Formula

I = Interaction strength
P₁, P₂ = Populations
d = Distance between cities
k = Constant (adjustable)

Legend

City (size = population)

Interaction link (thickness = strength)

Selected pair highlight

Gravity ModelSpatial InteractionMigration

Cities:6

Max Interaction:—

Selected:None

City A

—

City B

—

Distance

—

miles

Interaction

—

D Exponent

2

City Set

Distance Exponent 2

Higher = distance matters more

Constant k 1.0

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Calculation

Quick Quiz▼

1. If the distance between two cities doubles, interaction:

Doubles Halves Drops to 1/4 Stays the same

2. The gravity model is most similar to Newton's law of:

Inertia Universal gravitation Action-reaction Thermodynamics

3. Which factor would INCREASE interaction most?

Decrease one city's population Double both populations Double the distance Increase the exponent