A tool for operating on a workpiece, the tool comprising: a motion actuator configured to be coupled to a working surface to engage the workpiece; a controller coupled to the motion actuator to responsively vary a speed of the motion actuator and an operating speed of the working surface within the range of an initial speed and a max speed, and configured to respond to a derived force that represents an amount of force an operator applies between the workpiece and the working surface, wherein the controller is further configured, under both acceleration and deceleration, to allow the operator with an applied force to manageably change simultaneously both a rate of work on the workpiece and the operating speed of the working surface according to a sensitivity profile expressing a relationship between the derived amount of force and the operating speed of the working surface wherein the controller is configured to: derive a first derived force during a first time interval; set a first operating speed based on the sensitivity profile; derive a second derived force during a second time interval; when the second derived force is greater than the first derived force by a first predetermined amount, adjusting to a second operating speed based on the sensitivity profile and the second derived force; when the second derived force is less than the first derived force by a second predetermined amount, adjusting to a third operating speed based on the sensitivity profile and the second derived force; when the second derived force is determined to be less than the first derived force plus the first predetermined amount and greater than the first derived force minus the second predetermined amount, adjusting to a fourth operating speed based on the sensitivity profile and the second derived force. a motion actuator configured to be coupled to a working surface to engage the workpiece; a controller coupled to the motion actuator to responsively vary a speed of the motion actuator and an operating speed of the working surface within the range of an initial speed and a max speed, and configured to respond to a derived force that represents an amount of force an operator applies between the workpiece and the working surface, wherein the controller is further configured, under both acceleration and deceleration, to allow the operator with an applied force to manageably change simultaneously both a rate of work on the workpiece and the operating speed of the working surface according to a sensitivity profile expressing a relationship between the derived amount of force and the operating speed of the working surface wherein the controller is configured to: derive a first derived force during a first time interval; set a first operating speed based on the sensitivity profile; derive a second derived force during a second time interval; when the second derived force is greater than the first derived force by a first predetermined amount, adjusting to a second operating speed based on the sensitivity profile and the second derived force; when the second derived force is less than the first derived force by a second predetermined amount, adjusting to a third operating speed based on the sensitivity profile and the second derived force; when the second derived force is determined to be less than the first derived force plus the first predetermined amount and greater than the first derived force minus the second predetermined amount, adjusting to a fourth operating speed based on the sensitivity profile and the second derived force. derive a first derived force during a first time interval; set a first operating speed based on the sensitivity profile; derive a second derived force during a second time interval; when the second derived force is greater than the first derived force by a first predetermined amount, adjusting to a second operating speed based on the sensitivity profile and the second derived force; when the second derived force is less than the first derived force by a second predetermined amount, adjusting to a third operating speed based on the sensitivity profile and the second derived force; when the second derived force is determined to be less than the first derived force plus the first predetermined amount and greater than the first derived force minus the second predetermined amount, adjusting to a fourth operating speed based on the sensitivity profile and the second derived force.