FORCES & MOVEMENT
Small weight. Big effect.
Can a lighter load balance a heavier one? Find your balance.
Learning by doing
Left load
Right load
About this model & how to use it
Drag the coloured loads, or use the sliders with touch or arrow keys. Enable Rotate view, then drag the background to look around; turn it off for easier load movement. Reset restores the starting setup and camera.
We use g = 10 N/kg for this lesson (a rounded value). The uniform beam’s own weight acts at the pivot, so it contributes no moment. Loads are ideal point masses attached at the marked beam positions; the blocks are visual handles. Each adjustment restarts a release from horizontal. Gravity and damping determine the motion, with mechanical stops at ±12°. A beam resting on a stop is not balanced. The stops supply an additional reaction.
Along-beam distances are measured from the pivot. For tilt θ, the perpendicular distance is the along-beam distance × cos θ. The horizontal distance guides show this projection. Force arrows show the two loads’ weights only, with lengths proportional to force; support reactions are omitted. This is a teaching model, not a full rigid-body simulation.