One embodiment of a shock apparatus comprises at least one linear impact object capable of movement along a first substantially linear path; a rotational impact object capable of rotation about an axis of rotation and movement along a second substantially linear path parallel to the first substantially linear path, a mass of the linear impact object being greater than an effective mass of the rotational impact object; and a guide to guide the movement of the linear and rotational impact objects along the first and second substantially linear parallel paths. In one embodiment, the linear impact object comprises an impact portion for impacting the rotational impact object, the impact portion having a selectable position, and selecting the position determining the relative proportion of rotational and linear shock accelerations which an impact between the linear impact object and the rotational impact object provides to the rotational impact object.