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## 'Swings and Roundabouts' printed from http://nrich.maths.org/

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$O$ is the centre of the balance, and $X$ is the position of
the initially empty hook.

If you leave the hook at $X$ empty, what angle does $OX$ make to
the vertical once the balance settles?

If you were to attach a weight of $1$ unit at $X$ , what do you
think the angle might be?

Were you right?

If you were to attach a weight of $2$ units at $X$ what do you
think the angle might be?

Right that time?

You only need the $1$ and $2$ unit weights for the problem set but
the others are there to let you explore, conjecture and test - have
fun.