Physics WORK, ENERGY AND POWER

Conservative Force

When the total work done by a force F acting as an object moves over any closed path is zero, the force is conservative. Mathematically.

`ointvecF.dvecr=0` (conservative force)

Suppose we move an object along the straight path between point A and B shown in figure, along which a conservative force acts; Jet the work done by the conservative force be `W_(AB)`. Since the work done over any closed path is zero, the work `W_(BA)` done in moving back from B to A must be `-W_(AB)` whether we return along the straight path or the curved path or any other path. So, going from A to B involves work `W_(AB)` regardless of the path taken.

The work done by a conservative force in moving between two points is independent of the path taken:

mathematically, `int_A^BvecF.dvecr` depends only on the A end points A and B, not on the path between them.

These include force due to gravity(mg), spring force, electrostatic force etc.

Non-Conservative Force

Work done by non-conservative forces depends on path also. Least work is done for straight line path and any curved path it involves different work. These include frictional force, viscous force etc.

 
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