Conservative systems: A system is said to be conservative if no energy is added or lost from the system during movement. This is an idealised system but one that can be used to aid the solution of many problems. In real structures internal friction forces will do work and damping will dissipate energy.
Conservation of energy means that the total energy at two different positions or at two different times is the same in a conservative system.
Conservation of momentum indicates that the momentum of a system is the same at two different times when the resulting external force is zero between those two times.
- Energy can be transformed from one form to another, for instance, mechanical energy can be changed into electrical energy.
- For a conservative system, the total energy is constant and a body once moved will continue to move or to vibrate. During motion there is a constant exchange between potential energy and kinetic energy.
- For a non-conservative system, energy has to be added continuously to maintain motion.