Can You Balance the Scale?

Can you balance the scale? Drag a weight to the exact position that counteracts a fixed weight on the other side. One weight is pinned at a fixed distance from the pivot; you drag the other weight along the arm to the position where torques equalize and the seesaw levels out. Your score is the percentage error in torque balance. It's applied physics intuition: force × distance, estimated without equations.

How to Play

1. A seesaw appears with one fixed weight at a marked position.
2. Drag the free weight along the other arm to balance the scale.
3. Release. The seesaw tips to show how close you were.
4. Your score comes from the torque imbalance, measured as a percentage of the fixed weight's torque.

Why It's Hard

Torque is distance × force, but intuitive physics treats balance as "equal weight near the middle", a wrong model. When the fixed weight is light but far from the pivot, you must place your heavier weight close in. Most people place the weight proportional to mass rather than inversely proportional to mass, systematically over-compensating or under-compensating.

Tips

• The key equation: d1 × w1 = d2 × w2. If the fixed weight is twice as heavy and sits at position 3, your weight needs to go at position 6.
• Use the pivot as your reference: note the fixed weight's distance, then divide by the mass ratio to find your target position.
• If both weights are the same mass, place yours at the mirror position of the fixed weight.

FAQ

Are the weight values shown?

Yes, both weights are labeled with their relative masses. The challenge is combining that with the visual distance to compute the correct position.

What torque error is a perfect score?

Under 2% torque error is excellent. Under 5% is solid. First attempts typically land around 10–15% without applying the torque formula.

Is this the same as a moment/lever problem in physics?

Exactly. This is a first-class lever (pivot in the middle). The torque balance principle: sum of clockwise moments = sum of counterclockwise moments.