In a slider-crank mechanism, the motion is not uniform due to the varying angle between the crank and the connecting rod. The motion of segment AB can be studied by attaching a fixed reference system at point O and an additional translating frame of reference at point A. The absolute linear velocity of point B is expressed as the vector sum of the absolute linear velocity of point A and the relative velocity of point B with respect to point A. Taking the time derivatives gives the absolute acceleration of point B, which is the vector sum of the absolute acceleration of point A and the relative acceleration of point B with respect to point A. The motion of point B with respect to point A is a circular path, so the relative acceleration of point B is expressed as normal and tangential components. The motion of point B is then the result of the linear acceleration of point A, the angular acceleration, and the angular velocity of point B with respect to point A.