1. Newton’s equations of motion 2. Holonomic constraints are those given by equations of the form $$\phi _k \left( \vec r _1, ..., \vec r _N, t \right) = 0, k = 1, ...$$ where \(\phi _k \left( \vec r_1, ..., \vec r_N, t \right)\) are functions of the position vectors \(\vec r_\alpha\) of the particles making up the system. Our discussion will be concerned exclusively with holonomic constraints 3. The forces of constraints have the property that the total work done by all forces of constraints on a system under a small virtual displacement is zero.