Examples of different types of scales include spring scales, floor scales, platform scales and bench scales. Some more rudimentary scale types include equal-arm beam scales, pendulum scales and steelyard scales.
Spring scales vary in complexity, but they all contain a spring attached to a hook, to which the user attaches an object to measure its weight. This type of scale works based on Hooke's law, which holds that the displacement a spring stretches after applying a force is directly proportional to the magnitude of that force.
Floor scales have many practical uses, ranging from industrial applications to their use in veterinary clinics to monitor pets' weights. Their position on the floor makes them a great option for weighing very large loads that are difficult or impossible to lift. Platform scales, which are similar but consist of a platform slightly raised above the ground, are also useful for weighing large loads.
Simplistic equal-arm scales were the earliest type of scales to become available. An equal-arm beam scale consists of a beam with two arms of equal size on either side. Each arm has a pan attached to it. To use this type of scale, one first places an object in one of the two pans. Then, the user continues to add objects of known weight to the other pan until the two loads balance.