1.3.1 Speed
You may have noticed that when I animate a path by tracing the movement of a point, the dots along the path are not evenly spaced apart. Unsurprisingly this is related to the way the vector is changing. In the GeoGebra applet below, a path is animated on the left screen while the length of the velocity vector is tracked on the right screen.
The length of the velocity vector is called the speed of the path . That is:
The speed of the path is the scalar quantity .
Why do you think we chose the word "speed" to describe this scalar quantity?