As you animate an object by moving it from one location to another at different points in time, an animation path appears in the Modeling window. (You must have the Show Animation Paths command in the Selection menu enabled in order for animation paths to show.) This path represents the position of the object at different points in time.
Each time you move the object, an event marker is placed at the current time on the timeline in the Project window, and a control point appears along the path in the Modeling window.
Blue knots between the event markers represent frames. For example, if the frame rate is set at 15 frames per second, and the event markers are placed at precisely one-second intervals, then 15 knots are placed along the path between each event marker. The distance between these knots indicates the distance the object travels between frames.
You can move the event markers along the timeline in the Project window to change the object's pacing or its sequence in the animation. Just grab the marker on the timeline in the Project window and slide it to position it anywhere along its timeline.
The object's velocity is determined by the distance it travels during a specific period of time. (Velocity = distance/time.) So the greater the distance between markers (the more distance the object travels), the higher the velocity of the object. The closer together the event markers, the slower the speed of the object.
If you change the spacing between event markers, the spacing of the knots also changes to reflect the change in time.
In this example, the frame rate is still 15 frames per second. Now there are 26 frames between the first two event markers, and only four frames between the second and third event markers. So, the sphere's motion would be uniformly slow between the first two markers, and then move much faster between the second and third marker.
Moving the second marker the other direction, to approximately one-half second, has the opposite effect. Now the sphere's motion is faster in the first half-second, then moves slower (but at a uniform velocity) between the second and third event markers. The distance between markers remains the same, but the time between markers has changed.