In this paper we derive, directly from the Nambu-Goto action, the relevant
components of the acceleration of cosmological featureless p-branes,
extending previous analysis based on the field theory equations in the
thin-brane limit. The component of the acceleration parallel to the velocity is
at the core of the velocity-dependent one-scale model for the evolution of
p-brane networks. We use this model to show that, in a decelerating expanding
universe in which the p-branes are relevant cosmologically, interactions
cannot lead to frustration, except for fine-tuned non-relativistic networks
with a dimensionless curvature parameter k≪1. We discuss the implications
of our findings for the cosmological evolution of p-brane networks.Comment: 6 page