o
o
The work done by the conservative force depends only on the end points .
A third definition states that the work done by this force in a closed path is zero .
o The total mechanical energy of a system is conserved if the forces , doing work on it , are conservative .
Potential energy of spring o
o
The spring force is an example of a variable force , which is conservative .
In an ideal spring , Fs = − kx , this force law for the spring is called Hooke ’ s law .
o The constant k is called the spring constant . Its unit is N m -1 .