Force

FORCE. By the name F. is meant the cause that imparts to a material point acceleration in one direction or another. The measure of F. is the numerical value of the product of mass (m) by the magnitude of acceleration (a): F=ma. Expressed in absolute units, the unit of F. is called the dyne (dyn). The concept of F. is closely connected with the concept of the ability to overcome resistance or to perform work; in this sense, F. is usually evaluated for one or another mechanical system. It is clear from this that the magnitude of F. can be judged by the magnitude of the work it produces. The force of animals is directly dependent on the strength of their muscles and their total mass, but it must be borne in mind that the strength of muscles is not the same, not only of different animals, but also of different muscles of the same animal. Therefore, for comparison, the so-called "absolute muscular strength" is used. According to Weber, it is equal to the load that the maximally excitable muscle can just barely lift, but which does not stretch it. Relative to 1 cm² of cross-sectional area, absolute F. serves as a measure of comparison for the muscles of different animals. Thus, for example, the absolute strength of human muscles is on average estimated at 7-8 kg, of frogs-1-3 kg, of beetles-4-7 kg, and in some species of mollusks-up to 12 kg. The concept of F. should not be confused with the concept of power (see Human Power). Measurements of the force of individual muscle groups using dynamometers (see Dynamometry) as a valuable indicator of their functional activity are often used in physical education, as well as for diagnostic purposes in diseases of the muscular and nervous systems.