A weighing scale is a measuring instrument to determine the mass or weight of an object. A spring scale measures weight by the distance a spring deflects with his load. A balance compares the torque on the arm due to the weight of the sample pair in the arm due to a standard reference weight using a horizontal lever. The balances are different scales in a mass balance measurements (or more specifically gravitational mass), while a scale measures weight (or, more specifically, whether tension or compression force of constraint provided by scale). scales are used in many industrial and commercial applications, and feather products to load trucks with trailers are sold by weight. Specialized medical scales and bathroom scales are used to measure the body weight of humans.