The refinements are almost done
http://weelookang.blogspot.sg/2012/11/address-learning-difficulties-in.html
eduLab AJC page:
https://sites.google.com/site/lookang/collision-carts-dynamics-ajc
download and also attached
https://sites.google.com/site/lookang/collision-carts-dynamics-ajc/ejs_Momentum1DForceModel01.jar?attredirects=0&d=1

1. change in area size to mass for visual impact, area change according to mass now.
2. clearer arrows of contact force, done.
3. some other fixes like better graphics control click 1 show all mom,ke,forces
4. mouse and elephant graphics, I doubt it helps but I will try with your pictures, you wish to provide your picture of a mouse and elephant?