jousivaaka

Jousivaaka, literally “spring scale” in Finnish, is a mechanical instrument used to measure weight or force by the extension of a calibrated spring. It operates on the simple principle that a spring obeys Hooke’s law, F = kx, with F the force, k the spring constant, and x the spring’s displacement.

A jousivaaka typically consists of a rigid frame, a spring, a pointer moving along a calibrated scale, and a hook or weighing pan to hold the object. Most models display a reading in newtons, while some are labeled to give an equivalent mass in kilograms based on standard gravity. Some designs also show both readings.

Common configurations include hanging scales that measure weight by tension in the spring, and platform or handheld scales where the load is supported by a pan or grip. Calibration is performed with known weights to set the zero point and scaling. Accuracy depends on spring wear, temperature, and nonlinearity; regular calibration is recommended.

Jousivaaka are simple, robust, and inexpensive, requiring no power, but are generally less precise and less suitable for high-precision measurements than electronic load cells or digital scales. They remain useful for quick, rough measurements and for educational demonstrations of force and weight.

Uses include education, demonstrations of basic physics, and weight measurements in markets or laboratories where a fast, low-cost reading is sufficient. Related devices include dynamometers, force gauges, and load cells.