causes a physical separation of the cutting element and the rock thus conventionally stress energy for causing a subsequent fracture begins to build only after the cutting element re establishes an interface with the rock at point 20 at point 20 rotation of the drill bit begins to restore the lost stress energy until the rock again fractures at point 22 thus it should be appreciated that for line 10 the area denoted with numeral 24 represents an initial stored stress energy for causing an initial rock fracture the area denoted with numeral 25 represents the amount of stress energy released or lost by the initial rock fracture and the area denoted with numeral 28 represents the amount of energy restored to cause a subsequent rock fracture in one embodiment of the present invention a controlled torsional force is momentarily superimposed on the constant drill string rotation at point 18 such that the cutting element temporarily accelerates to at least maintain contact with the fracturing rock and thereby maintain the cutting element and rock surface interface stress level at least until the drill bit at its constant rotational speed can apply the cutting element and rock surface interface stress level which is denoted as point 30 however the controlled torsional force does not change the average bit rotation speed thus point 30 represents the point at which the momentary torsional force is no longer applied to the drill bit stated differently at point 18 the cutting element speeds up to stay with the fracturing rock until the drill string rotating the drill bit u201c catches up u201d at point 30 thus the cutting element and rock surface interface experiences a significantly lower loss of stored stress energy this is advantageous because the remaining stored stress energy can be.