Weighing scale
The balance (also balance scale, beam balance and laboratory balance) was the first mass measuring instrument invented. In its traditional form, it consists of a pivoted horizontal lever with arms of equal lengththe beamand a weighing pan suspended from each arm (hence the plural name ""scales" for a weighing instrument). The unknown mass is placed in one pan and standard masses are added to the other pan until the beam is as close to equilibrium as possible. In precision balances, a more accurate determination of the mass is given by the position of a sliding mass moved along a graduated scale. Technically, a balance compares weight rather than mass, but, in a given gravitational field (such as Earth's gravity), the weight of an object is proportional to its mass, so the standard masses used with balances are usually labeled in units of mass (e.g. g or kg).
1:24 scale
1:24 scale is a very popular size for automobile models such as injection-molded plastic model kits or metal die-cast toys, which are built and collected by both children and adults. 1:24 means that a unit of measurement, such as one inch or one centimeter, on the model represents 24 units on the actual object. An example would be one inch of length on a model automobile would represent 24 inches on the real vehicle. Primarily automobile models are made in this scale, with a few examples of tractor trailers and other larger equipment. In the United States there is a very minor variation of the 1:24 scale, where many automobile plastic model kits are scaled at 1:25.
1:24 is the largest of the traditional slot car sizes - and the earliest. Lionel's (USA) 1:24 electric autos of 1912-1916 became the first known commercial slot cars. In 1955, the Model Automobile Racing Association of Kalamazoo, Michigan, built the first track for electric rail-racing (the short-lived immediate predecessor to slot racing) in the US. Unlike the seminal Southport (UK) track that inspired it, the MARA table was designed for 1:24 as well as competition. With that beginning, the US adopted 1:24 as the primary scale for serious competition during the heyday of slot car racing in the 1960s, while Britain and Europe favored 1:32, and have continued to do so.