I have a thought experiment I cannot resolve. Maybe someone smarter than I can resolve this. Suppose we have a long, thin rod, rotating in the counter-clockwise direction around a pivot axis which is at the end of the rod with an initial angular velocity equal to w. The axis is connected to a second object which we will denote as the slider. The slider can slide along a straight, linear track. We assume no friction in this experiment. Initially, we prevent the slider from moving, but at some point in time when the rotator has passed its zero degree position with respect to the x-axis of an x-y coordinate system, we release the mechanism which holds the slider stationary. Immediately, the slider begins to accelerate in the positive y-direction. This is because of the y-component of the centrifugual reactive force acting on the axis which is attached to the slider. This force is equal and opposite to the centripetal force which acts on the center of mass of the rod. With respect to an observer in the frame of the slider, he would observe the angular velocity of the rod will slow down due to the gravitational field in his frame caused by the increasing acceleration of the slider. The initial angular velocity w of the rod will therefore decrease and this decrease must also be observed by an observer in a laboratory inertial frame. What torque acting on the center of mass of the rod with respect to an inertial frame would cause the angular velocity of the rod to decrease? Obviously, there is no "gravitational field" to slow it down.