  The packing of hard-core particles in contact with their neighbors is considered as the simplest model of disordered particulate media. We formulate the statically determinate problem which allows analytical investigation of the statistical distribution of contact force magnitude. The toy-model of the Boltzmann type equation for the probability of contact force distribution is formulated and studied. An experimentally observed exponential distribution is derived. 
The toy-model of the Boltzmann type equation for the contact force   distribution in disordered packings of particles