A spring balance is a weighing apparatus used in industries to measure the mass of different loads. It is also used in science experiments as a basic accelerometer. Spring balances are not legal for use in trade because the theory used to calibrate them is only approximate. Similarly, the spring used by the balance can become permanently stretched due to continuous use.
A spring balance is calibrated with equally spaced markings indicating pounds or kilograms. It employs Hooke’s law, which states that the force required to extend a spring is relative to the distance that the spring is pulled out from its position of rest. The first spring balance was invented in Europe in 1771, and the accuracy and reliability of the models have been greatly improved. Since then, the cost of a spring balance has significantly reduced, with some being made with anti-corrosion materials.
They come in different sizes and depend on the weight of the loads they are designed to measure. If two similar spring balances are hung in a series, one below the other, and a load is hung on the spring balance at the bottom, both scales read the same values. Small spring balances are usually made with springs of a smaller spring constant. Those designed for domestic use are called fish scales.