Skeleton Biomechanics: Bones as Levers (3D)

This is a real articulated skeletal joint rendered in 3D, switchable between the three classes of lever the human body actually uses: a neck joint (Class 1, fulcrum between load and effort), an ankle in a calf raise (Class 2, load between fulcrum and effort) and an elbow doing a bicep curl (Class 3, effort between fulcrum and load — the most common arrangement in the body). Every frame, the required muscle force is recomputed from genuine torque balance as you change the muscle's attachment distance from the joint, the load's distance and weight, or the joint angle, and the muscle cylinder's thickness and color respond live so you can see mechanical advantage in action, not a canned animation.