Torque & Balance
Hang a mass at a chosen distance from the pivot on each side of a beam, add weight to the beam itself, and shift the pivot off centre — watch the beam swing down on the heavier side and settle, or stay level when the two torques exactly match.
Preview — sign up free to change the numbers yourself
What you can adjust
- Left mass
- 0.5 – 20 kg
- Right mass
- 0.5 – 20 kg
- Left distance from pivot
- 0.2 – 1.5 m
- Right distance from pivot
- 0.2 – 1.5 m
- Beam mass
- 0 – 8 kg
- Pivot offset from beam centre
- -0.5 – 0.5 m
Torque is force times distance from the pivot, not mass alone — more mass here raises this side's torque in direct proportion, the same as sliding it further out would.
Balances against the left side's mass x distance, not against the left mass alone.
A small mass far from the pivot can out-torque a large mass close in — torque only cares about the product of mass and distance.
Same rule as the left side: moving this mass further out increases its torque exactly as much as adding mass would.
The beam's own weight acts at its centre, not at the pivot — with the pivot centred it contributes no torque at all; it only starts to matter once the pivot is off-centre.
Moving the pivot off-centre puts more of the beam's own length — and so more of its weight — on one side, adding a third torque term that can tip the beam even when the two hanging masses' torques are perfectly matched.
About this simulation
What it shows
A beam on a pivot carries a mass on each side. It swings down on the heavier side and settles, or stays level when the turning effects match.
The key idea
Turning effect (torque) is force times distance from the pivot. The beam balances when the torques on the two sides are equal, so a small mass far out can balance a big mass close in.
Try this
Set Left mass to 10 kg and Left distance from pivot to 0.5 m: it balances the 5 kg at 1 m on the right, because 10 × 0.5 equals 5 × 1.