Finishes: Colors & Stains

What is D'Alembert's Principle? For a system of mass of particles, the sum of the difference of the force acting on the system and the time derivatives of the momenta is zero when projected onto any virtual displacement.

A theorem in fluid mechanics which states that no forces act on a body moving at constant velocity in a straight line through a large mass of incompressible, inviscid fluid which was initially at rest (or in uniform motion).