Material Detail

I spent about 30-45 minutes trying this out. The item consists of four applets.
The first represents cannon balls colliding with a railway car. The remaining
three represent the collision of two railway cars, one of which is initially at
rest.
The applets contribute little to the conceptual understanding of momentum or
its conservation. Two can be used to test quantitative predictions, but only for
totally inelastic collisions (assuming that the cannon ball collisions are
totally inelastic, which is not stated nor subject to confirmation). The
remaining two can be used as tests of students' ability to perform quantitative
calculations involving momentum conservation in totally inelastic collisions.
Two of the four questions with the first applet require only the ability to
count; that is, no physics understanding is required on the part of the student.
Furthermore, the lack of specification of units reinforces the undesirable
tendency of students to ignore units. Most annoyingly, some of the applets are
VERY slow to develop.

Technical Remarks:

Good applet with clean graphics. Having the mass and momentum variable is somewhat awkward.