Balance scales work by comparing the mass of an unknown object to known masses, achieving equilibrium when the masses on both sides are equal.
Here's a breakdown of the process:
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Placement of Objects: An object with an unknown mass is placed on one pan of the balance scale.
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Adding Known Weights: Standardized weights (objects with precisely known masses) are added to the other pan.
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Achieving Equilibrium: Weights are added or removed from the known-mass pan until the scale is perfectly balanced. This perfect balance represents a state of mechanical equilibrium. The indicator, such as a pointer, rests at neutral or zero.
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Equal Masses: When the scale is balanced, the mass of the unknown object on one pan is equal to the total mass of the known weights on the other pan.
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Determining Unknown Mass: The mass of the unknown object is then simply determined by adding up the values of the known weights.
In essence, a balance scale operates on the principle of direct mass comparison, offering a precise method for determining the mass of an object without relying on gravity (unlike spring scales). The scale essentially compares the downward force exerted by the object with unknown mass to the downward force exerted by the calibrated weights. A perfectly balanced scale indicates these forces are equal, therefore, the masses are equal.
