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Constrained impacts with friction frequently exist in mechanical systems suchas robotic arms, hard disk drives and other mechanisms. Such discontinuouscontacts, if not designed and analysed properly, can lead to malfunctions. Inparticular, for the analysis of problems that involve eccentric collisions and reversalof friction force, use of stereomechanical impact theory with coecient ofrestitution can produce paradoxical energy increase. Alternatively, continuummodels, which provide more detailed analysis for such problems, can be used,however they are computationally tedious. Instead, here, contact is described bycompliant elements with friction and applied to a physical pendulum.In this thesis, impact-momentum relations for general three-dimensional freecollisions are modied for a pendulum which exemplies an impact with frictionand constraint. Inclusion of tangential compliance to model enables the modelto demonstrate tangential force reversals and their transition between stick andslip, which is demonstrated using a sphere and a slender rod obliquely collidingwith a rough massive plane.Use of compliant elements to describe impact by a planar pendulum producesdierences in the behavior of a constrained system compared with free impacts.For instance, in free collisions an impact that starts with an initial sticking,is always followed by sliding. However, in a pendulum if the contact beginsby sticking, it continues to stick throughout the duration of impact. Anotherdierence appears when contact starts with an initial sliding. In free impact,sliding is followed by sticking and sliding, then the body rebounds unless thecollision is inelastic. However, in the constrained case wedging of the pendulumis observed if initial angle of collision is below a critical value for a speciedfriction coecient.