System in which the forces acting on a body do work which is independent of the path followed by the body.

For example, when gravity is the only force acting on a body the system is conservative. However, this is no longer the case if friction is acting on the body.

In a conservative system it can be shown that the forces acting on a body are equal to spatial derivative of the potential energy. The potential energy (V) due to gravity is **mgh** where **m** is the mass of the body, g is the acceleration due to gravity and **h** is the height of the body above the ground. In this case, the force is given by,

**F**=dV/dh=mg

If a ball is thrown vertically in the air and reaches a height **h** or if it is thrown at any other angle to reach the same height, the potential energy of the ball will be **mgh** regardless of the path taken.