1. This paper introduces the simulator Impulse and examine how the impulsive collision resolution may be extended to constrained systems. 2. Many simulators for simple physical systems employ constraint-based approaches. Constraints are used to describe the interactions between objects which often occur only through physical contact. A large variety of contact interactions can be modeled efficiently and accurately by hard constraints, however the method is not well suited to some situations, where all of contact occurrences must be detected and processed, and new equations of motion for the system must be derived at every transition. 3. The main idea of Impulse is that all contact interactions whether colliding, rolling, sliding or resting are affected via trains of collisions. There are no global constraints governing the motion of the objects. Instead the correct macroscopic behavior results from processing individual collisions. However, impulse-based contact modeling is not always a good choice, especially in situations which involve prolonged close contact. 4. Main challenges to combine these two approaches: computing colliding constrained bodies, switching between constraints and impulses and collision detection.