# Notes of Mechanics by Kaleem Arif

If a particle is moving down on an inclined plane, then constraint on its motion is its contact with plane. Any displacement along the plane is consistent with the constraint. If the force does no virtual work then the constraint is called workless. For Single Particle: A particle subjected to workless constraint is in equilibrium iff zero virtual work done by the applied force in any arbitrary infinitesimal displacement consistent with the constraint... (See more in the PDF)