This article studies the impact of mobility when mobiles are under a simultaneous power and rate assignment scheme based on a fair assignment policy. Using a fluid model for expressing the long-range impact of neighboring cells, we are able to derive an analytical expression of the impact of one moving mobile to a fixed one, both being under a fair policy of rate assignment. These policies include max-min, Nash equilibria, harmonic equilibria and many others. We validate our model on a stochastic geometric model where we measure the elasticity of the rate of the moving terminal and show more complex situations when more than two mobiles influence each other. As a result, we show how mobility impacts a network of mobile terminals and derive conclusions on how to correctly manage such a network.