Are you in the U.S. for AAPT meeting now?

I just created a quick verison of what you might need.

You can drag the gray dot to different height.
The [u]string[/u] mode is what you want.

The following applet can be used to illustrate
1. conservation of energy
2. Collision between two particles. (two partialces are the same mass in the current version. I will add options for different mass later).
3. Pendulum or circular motion in vertical plane.

/htdocs/ntnujava/ejsuser/2/users/ntnu/fkh/potentialenergycircularmotion_pkg/potentialenergycircularmotion.propertiesFull 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(1433.8kB):double click downloaded file to run it. (3 times by 3 users) , Download EJS source (5 times by 3 users) View EJS source