Speed Vector: Use this tool to give body elements speeds during Run mode. To attach the velocity vector, click on the target body, then drag out the vector in the direction and to the length you desire. The velocity vector appears as a thin red line with a half arrow above or to the right of the body (except when you subject the body to a central thrusting force, when the speed vector appears as a red arrow originating from the center of the body).

You can later change the length and direction of the speed vector by resizing it, or by setting the strength (i.e., magnitude, in m/s) and direction (degrees) in the vector's Properties Box. You can only attach one speed vector to any single body.

Since bodies can only move in either the horizontal or vertical directions (never along a diagonal), you cannot place horizontal speed vectors on a body with vertical force or speed vectors. The reverse is also true.

In the Properties Box, you can also set the label for the speed vector (default is Speed) and show (or not show) the vector's label or length (magnitude). You can also opt to show (or hide) the speed vector during Stop mode, Run mode, or Pause mode.

With the Select tool, you can change the direction of the speed vector. If you hold down the Shift key, you can rotate the speed vector 180 degrees using the arrow keys.