F1 is the force exerted on the heavy box, which is equal to F1 and is resisted by the lesser frictional force f1. F = Fs, which is the maximum static frictional force, is required for the box to move. On the y-axis, this force corresponds to the frictional force fs.

When Fk Fs is applied to the body and it begins to move, the frictional force diminishes, resulting in reduced friction.