Friction is the classic example of a force that is not conservative. It changes kinetic and potential energy into other forms such as heat and sound. A drag force such as air resistance is also not conservative. It dissipates energy in the form of heat and the kinetic energy that is given to the air. Finally, the forces produced by human muscles are also nonconservative. They convert chemical energy into mechanical energy, and dissipate energy as heat.
Work Step by Step
Conservative forces are ones whose work is independent of the path taken between initial and final positions.