POOL can detect turtle collisions, which are programatically handled with use of the turtlecollision and turtleinteraction events (see also description in the reference manual). This functionality is used by the elastic and elastic_m1 classes, from which we start to build the standard POOL models library. This project illustrates how to use elastic models.

You can set the direction and the initial energy of the active turtle by moving the mouse. Then click to start the turtle.

Each object of the elastic class can have its own value of mass. You can check it by uncommenting (setmass 20) @ :u line in the code.
If all objects in a simulation have equal masses, then the elastic_m1 class can be used. It performs simplified and faster calculations.