Weighing Balance and Scales

A spring scale measures weight by the distance a spring deflects under its load. A balance compares the torque on the arm due to the sample weight to the torque on the arm due to a standard reference weight using a horizontal lever. Balances are different from scales, in that a balance measures mass (or more specifically gravitational mass), whereas a scale measures weight (or more specifically, either the tension or compressionforce of constraint provided by the scale). Weighingscales are used in many industrial and commercial applications, and products from feathers to loaded tractor-trailers are sold by weight.