# Thread: weights and balance question

1. Hi, I recently acquired a sturdily built illuminated magnifier. It doesn't come with a base but has a fitting that could go into a socket. That's fine because I can build a box with a handle and load it with sand. My question would be is there a way to work out how heavy the base has to be with the arm at full extension? The bulk of the weight is in the head, which contains the glass magnifier, and that weighs 1kg. The distance from the pivot to the centre of the magnifier at full extension is 120cm. Your thoughts would be appreciated!
Julian

2.

3. The magnifier will exert a torque tending to tip over the magnifier. This torque is equal to the weight multiplied by the length of the lever arm. Counteracting this torque will be the weight of the base, with a center of gravity in the middle of the base, pivoting about the edge of the base. So you would take the radius of your base, and multiply that by the mass of the base. That number has to exceed 120 kilogram centimeters.

4. Thanks Harold, that makes sense. I shall have a play around with the figures.
Julian

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