Fulcra Applets (download is a zipped folder)
Single Fulcrum: predict whether an array of masses on a beam balance will balance when the supports area removed
Double Fulcrum: try to remove the masses by sliding them without allowing the beam to tip. Various diagrammatic assistance can be called upon!
2D Fulcra: explore the placing of masses on a table supported by a polygonal fulcrum.
Showing a single fulcrum balance beam with masses ready to be adjusted (and-or dragged) before supports removed
Showing a double fulcrum balanced: ready to slide masses so as to remove them the they are between the fulcra
Showing two 2D configurations. The triangle is the fulcrum. The red line indicates unbalanced; the blue lines indicate balance tolerance.