want to know some about force.

A conservative force is a force with the property that the work done in moving a particle between two points is independent of the path taken. The direction between the action of the force and that of the path has no relation to the definition of "consevative force".

Gravitational force is a conservative force because it satisfies the above definition. For example, an object that falls vertically by a height of 1 metre, say, under the action of gravity loses the same amount of energy as the same object that slides down a smooth inclined plane with a vertical fall of 1 metre.




2012-01-31 20:16:12 補充：
Q:WHY will the object loses energy ???the energy is conserved...
A: The object loses potential energy, but gain in kinetic energy. The total mechanical energy is conserved.