Hookes Law - Spring Force

Fs	= Force exerted by the spring. SI: N
k	= Spring Constant. SI: N/m
x	= Displacement from equilibrium position. SI: m

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Hook's Law Simulation
An object is connected to a spring whose spring constant k can be change along with the object's initial position. Displayed is the spring's force on the object as well a graphical display of the object's position and velocity as function of time. Hook's Law QT Movie

* The negative sign indicates that the spring force is a restoring force, i.e., the force F_s always acts in the opposite direction from the direction in which the system is displaced. Here we assume that the positive direction for values of x are the same as the positive values of the force.

* The origin has to be placed at the position where the spring system would be in static equilibrium for the equation F_s = -k x to be valid. This is the location were the net force on the object to which the spring is attached is equal to zero. If not, then F_s = -k(x - x_o) where x_o is equilibrium position relative to the origin.

* Springs are normally assumed to be massless so their inertia can be neglected. This also means that the force exerted by both ends of the spring are the same but in opposite directions.