Fill in the blanksQuestion 1 · Recall
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By the end you can state the principle of moments and use it to find an unknown force or distance on a balanced object.
The main symbols used in this lesson:
| Symbol | Meaning |
|---|---|
| weight |
A small child can balance an adult on a see-saw. The trick: sit much further from the pivot.
Balance doesn't need equal forces. It needs equal moments.
Principle of moments
For an object in equilibrium, the sum of the clockwise moments about any point equals the sum of the anticlockwise moments about the same point.
Worked example: Easy one first: the see-saw
A child sits from the pivot of a see-saw. How far from the pivot, on the other side, must a parent sit to balance?