Collisions and impacts are the principal reasons for impulsive motions, which we frequently see in dynamic responses of systems. Precise modelling of impacts is a challenging problem due to the lack of the accurate and commonly accepted constitutive law that governs their mechanics. Rigid-body approach and soft contact methods are discussed in this paper and examined in the presented numerical examples. The main focus is set to impacts in systems with multiple unilateral contacts and collisions with elastic elements of the reference. Parameters of interconnecting unilateral springs are under discussion.