Isaac: Solving Physics Problems Stated in English

This is a demonstration of the Isaac program, an Artificial Intelligence (AI) program that solves rigid body statics problems stated in English.

There are 37 problems that are predefined. You can solve one of these problems by entering the problem number.

You can also attempt to solve a new problem. Enter the text of the new problem, one sentence per line, in the input area; then select the "Try New Problem" command. However, no serious effort has been made to make Isaac robust for new problems, so not all new problems will work. An example of a new problem is: What force is required to lift one end of a pole?

Representations of Knowledge in a Program for Solving Physics Problems,'' Proc. 5th International Joint Conference on Artificial Intelligence (IJCAI-77), Cambridge, MA, August 1977, pp. 286-291.

You must have the Java virtual machine installed to run this demo; you can get it for Windows (msjavx86.exe) here.

The best things in life are free: this demo uses the free software Gnu Common Lisp (GCL), XGCL, X windows [see also XFree86], Java, and WeirdX, a Java implementation of an X server.


  1. If needed, edit your display name. It should end in :2.0, for example,
  2. Click to start the demo. Scroll down to see the interaction window and drawing window below..

The Isaac program solves physics problems stated in English, in the domain of rigid body statics.

To solve a predefined problem, click in the small box and enter the problem number (from 1 - 37), followed by Enter/Return.

To try a new problem, click in the first input line and enter a sentence, followed by Enter/Return. Repeat for each of the sentences of your problem. The program is not very robust for new problems, so it may not solve your problem. An example: What force is required to lift one end of a pole?

Gordon S. Novak Jr.