This paper analyses some aspects of the application of the generalized impulse-momentum balance equations to flexible multibody systems. These equations are the result of extending impulsive dynamics to the collision of flexible and constrained bodies. Application of the generalized impulse-momentum balance provides a system of algebraic equations that is solved for the velocity jumps and the impulses associated with the contact force and the reactions involved. As shown in this paper, the physical significance of the coefficient of restitution, which is included in the formulation to account for energy losses, can be misinterpreted. The floating frame of reference approach was used in combination with the finite element technique to describe flexibility and component mode synthesis to reduce the number of flexible co-ordinates in the collision problem studied. The number of elastic co-ordinates used to describe flexibility and the time step used in the numerical integration essentially influence the dynamic simulation of the impact process. The underlying message of this research is that the collision simulation entails solving many different balances. However, as shown in this paper, this is not the result of the real phenomenon of succession of impacts. These facts are illustrated with some numerical simulations of impacts of rigid bodies on flexible elements.