The system shown in Fig. 3↑ has two rigid bodies. The basic constraints are one-dimensional translation for both, no rotation for the left mass, and only one rotation degree of freedom for the right mass. This leaves three degrees of freedom total. However, in this case it is given that the circular mass rolls without slipping, resulting in a rolling constraint being imposed on the system. Mathematically, this constraint can be represented as x₂ = Rθ where θ is the rotation angle (in the figure, the angular velocity ω is identified instead of the angle). This constraint reduces the number of degrees of freedom from three to two for the system. An example problem in which this constraint is applied in developing equations of motion for the system shown is given here.