Why a long spanner beats a short one, and how a seesaw finds its balance. Place weights on a beam and see the torque — the turning effect of each, τ = m·g·d. Set the mass and distance on each side and the beam tips toward the larger torque, sitting level only when the moments match: mL·dL = mR·dR. A small mass far out can balance a big mass close in — the principle behind every lever. It all runs on your device.
You are in the Physics lab.
The two moments side by side: each bar is τ = m·g·d for that side. The beam sits level when the bars match; it tips toward the longer one.
What the two force arrows, the beam tilt and the moment bars are telling you.
On each side a coloured arrow drops straight down from the weight — that is its weight force, W = m·g, labelled in newtons. Gravity always points down, so the arrow stays vertical even as the beam tilts. Its turning effect depends on how far out it acts: the lever distance dL or dR is marked under the beam in metres, and the moment printed beside each box, τ = m·g·d, multiplies the two together.
The beam pivots on the fulcrum and settles at an angle set by the net torque, τR − τL. When one moment is larger the beam rotates that way and the Beam tilt readout shows the angle and direction; when the two moments match the net torque is zero and it sits level. The State badge reads Balanced, Tips left or Tips right to name what you are seeing.
The bar chart under the beam draws the two moments side by side. Balance is reached when the bars are the same length — that is mL·dL = mR·dR, with g cancelling from both sides. Because distance counts as much as mass, a small weight far out balances a big weight close in. The Mechanical advantage readout is the lever-arm ratio dL/dR — how much the longer arm multiplies a force.
A force, a distance, and the principle of moments that ties them together.
Torque, or moment, is the turning effect of a force about a pivot: τ = F·d. For a hanging weight the force is its weight m·g, so τ = m·g·d. Apply the same force further from the pivot and the torque grows — the reason a longer wrench turns a stubborn bolt a short one cannot. Slide a weight outward and its moment rises even though its mass has not changed.
A beam is balanced — in rotational equilibrium — when the anticlockwise moment equals the clockwise moment. With one weight per side that is mL·dL = mR·dR, and g cancels out. Because distance matters as much as mass, a light mass far from the pivot can hold up a heavy mass close to it — exactly what the Seesaw preset shows.
That trade-off is how a lever multiplies force: apply a modest effort far from the pivot to lift a large load near it, with mechanical advantage deffort/dload. Seesaws, wheelbarrows, crowbars and cranes all run on the same τ = F·d you are adjusting here — set the masses and distances and watch the beam find equilibrium.
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Record torque versus distance and angle, and the condition when the system balances.
Torque τ = rF·sinθ measures a force’s turning effect; it grows with lever arm and is largest when the force is perpendicular. A body is in rotational equilibrium when opposing torques balance to zero.
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