MOMENTS LAB

Beam & balance

Move a weight and compare its moment.

Prepared construction Balance challenge

BUILD

Drag to move an attachment.

Add a part

Drag to attach
or click to place

YOUR BALANCING BEAMBeam 1 selected

Tab selects parts. In Build, arrows adjust attachments. Enter opens Properties. Move adjusts attachments and pivots during motion; Pull applies a force. Ruler endpoints snap to apparatus. Focus ruler A or B and use arrows for precise measurements.

Start with a beam

Choose Parts, then Beam, and place it on the bench.

100%

Drag a weight or pivot to edit your build.

Experiment controls

Beam 1

Select a part

Teaching overlays

Masses Forces Moment arms Moments on the apparatus Centre of mass Show moment readings

Model settings

GravityDamping Gentle Ignore beam weight

Teaching approximation: beam inertia is retained.

Ideal 2D apparatus. Strings have no mass. Parts pass through each other. No friction, collisions or tangling.

Calculations

Challenge guidance

CONSTRUCTED ARRANGEMENT · AT REST

Moments about the pivot

Force-by-force calculation

Moment = force × perpendicular distance

Force	Magnitude / N	Perpendicular distance / m	Moment / N m

Moment readings are hidden for prediction. Use Show readings below the bench to reveal them.

Beam 1 · predicted at rest

↻ Clockwise0 N m

↺ Anticlockwise0 N m

Resultant moment0 N mBalanced moments

Choose a simulation

Switching modes keeps each construction in this tab. Reloading starts fresh. Reset is undoable.

A LITTLE HELP GETTING STARTED

Build something in balance.

Arrange your apparatus. In Build, drag a part onto a beam. Click a part instead if you prefer, then click its destination. A new beam in empty space gets its own support.
Make it yours. Drag weights, pivots and attachment rings. Open Properties for exact numbers, string lengths and parent attachments. Moving a branch carries everything below it. Add as many Anchor parts as you need, including during Run. Each adds a separate fixed support and string, keeping the pivot. Move the anchor or its beam attachment; set extra slack in Properties. To suspend a beam only from these anchors, select its beam and choose Remove pivot in Build.
Set it moving. Press Run. Move slides weights and pivots, holding motion until you release. Choose Pull to swing the apparatus with a pulling force. Pause freezes motion; Build returns to your designed arrangement.
Reveal the physics. Select a beam and turn on Forces, Moment arms or Moments. Use Ruler to measure between two draggable points; choose m or cm. It works during motion and while paused. Ruler points snap to pivots, beam ends and attachments; hold Alt for a free point. Focus the A or B button and use arrows for precise keyboard measurements. Every beam must balance, including the ones underneath.

Keyboard: Tab through parts on the canvas, arrows to move a selected attachment in Build (Shift for smaller steps), Enter for Properties, Escape to cancel placement, Delete to remove a part. Ctrl+Z / Ctrl+Y undo and redo. Space runs or pauses.

View: use +/− to zoom. Turn on Pan, or hold Space and drag the background. On touch screens, pinch to zoom and use Pan to move the view.

Progress and constructions stay in this tab only. Resetting a mode is undoable; reloading starts fresh.