What is the principle of virtual work?

The principle of virtual work states that the work done by internal forces in a system is zero.

The principle of virtual work is a fundamental concept in mechanics that is used to determine the equilibrium conditions of a system. It states that the work done by internal forces in a system is zero, which means that the net work done by external forces must also be zero for the system to be in equilibrium. This principle is based on the idea that if a system is in equilibrium, then any small virtual displacement of the system will not change its state of equilibrium.

The principle of virtual work can be used to solve problems in statics and dynamics. In statics, it is used to determine the forces acting on a structure in equilibrium. In dynamics, it is used to determine the motion of a system under the influence of external forces.

To apply the principle of virtual work, we consider a small virtual displacement of the system and calculate the work done by the external forces during this displacement. We then set this work equal to zero, since the system is in equilibrium. This allows us to solve for the unknown forces or motion of the system.

Overall, the principle of virtual work is a powerful tool in mechanics that allows us to determine the equilibrium conditions of a system and solve problems in statics and dynamics.