1: simulation of how vectors(e.g velocities) in 2-D can be added and / or subtracted to find the resultant vector. For instance the simulation can depict velocities of two ships moving relative to each other;

How about the following simulation.
You can drag to change velocity vectors and the relative velocity will be shown.

What need to be improved?

translate strings in simulation to different language format before download
Full screen applet or Problem viewing java?Add http://www.phy.ntnu.edu.tw/ to exception site list
Press the Alt key and the left mouse button to drag the applet off the browser and onto the desktop. This work is licensed under a Creative Commons Attribution 2.5 Taiwan License
Download EJS jar file(1417.4kB):double click downloaded file to run it. (17 times by 14 users) , Download EJS source View EJS source