The window "Parametric curve and velocity vector" displays the graph of X(t) (which you can alter in the appropriately labeled textbox), the point X(t

The window "Graph of speed s'(t)" displays the graph of s'(t) = ||X'(t)|| in cyan, with the area shaded in blue below it representing the integral of s'(t) from the minimum value of t to t

The window "Graph of arclength s(t)" displays the graph of s(t) obtained by integrating s'(t) as displayed in the "Graph of speed s'(t)" window.

To change t

[<]: Decrease t

[>]: Increase t

[<<]: Decrease t

[>>]: Increase t

By default, the demo shows the point tracing out the curve, so that only part of it is shown. To show the entire curve, check the box "Show entire curve" by clicking on it.