In the previous section,
Work and Energy was developed for a nonconservative system. However, in many problems there are only conservative forces which permits an alternative way to develop the energy balance equation.
A conservative force means that the work done by the force is independent of the path. Gravity and springs are conservative forces, but friction is not.
If there are only conservative forces, then the total energy at any point in time (or position) must be constant. Generally, conservative forces are grouped as potential (V) or kinetic (T) energy.
V_{1} + T_{1} = constant
If the total energy is constant, then the total energy at one point must equal the total energy at another point in the motion.

V_{1} + T_{1} = V_{2} + T_{2}


At any given time, all energy in a conservative system is defined as kinetic or potential energy. 