Force

force

1. Physics

a. a dynamic influence that changes a body from a state of rest to one of motion or changes its rate of motion. The magnitude of the force is equal to the product of the mass of the body and its acceleration

b. a static influence that produces an elastic strain in a body or system or bears weight.

2. Physics any operating influence that produces or tends to produce a change in a physical quantity

3. Criminal law violence unlawfully committed or threatened

4. Philosophy Logic that which an expression is normally used to achieve

5. in force (of a law) having legal validity or binding effect

Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005

Force

Force may be briefly described as that influence on a body which causes it to accelerate. In this way, force is defined through Newton's second law of motion.

This law states in part that the acceleration of a body is proportional to the resultant force exerted on the body and is inversely proportional to the mass of the body. An alternative procedure is to try to formulate a definition in terms of a standard force, for example, that necessary to stretch a particular spring a certain amount, or the gravitational attraction which the Earth exerts on a standard object. Even so, Newton's second law inextricably links mass and force. See Acceleration, Mass

One may choose either the absolute or the gravitational approach in selecting a standard particle or object. In the so-called absolute systems of units, it is said that the standard object has a mass of one unit. Then the second law of Newton defines unit force as that force which gives unit acceleration to the unit mass. Any other mass may in principle be compared with the standard mass (m) by subjecting it to unit force and measuring the acceleration ( a ), with which it varies inversely. By suitable appeal to experiment, it is possible to conclude that masses are scalar quantities and that forces are vector quantities which may be superimposed or resolved by the rules of vector addition and resolution.

In the absolute scheme, then, the equation F = m a is written for nonrelativistic mechanics; boldface type denotes vector quantities. This statement of the second law of Newton is in fact the definition of force. In the absolute system, mass is taken as a fundamental quantity and force is a derived unit of dimensions MLT^-2 (M = mass, L = length, T = time).

The gravitational system of units uses the attraction of the Earth for the standard object as the standard force. Newton's second law still couples force and mass, but since force is here taken as the fundamental quantity, mass becomes the derived factor of proportionality between force and the acceleration it produces. In particular, the standard force (the Earth's attraction for the standard object) produces in free fall what one measures as the gravitational acceleration, a vector quantity proportional to the standard force (weight) for any object. It follows from the use of Newton's second law as a defining relation that the mass of that object is m = w/g, with g the magnitude of the gravitational acceleration and w the magnitude of the weight. The derived quantity mass has dimensions FT² L^-1. See Free fall

McGraw-Hill Concise Encyclopedia of Physics. © 2002 by The McGraw-Hill Companies, Inc.

force

Symbol: F . According to Newton's laws of motion, any physical agency that alters or attempts to alter a body's state of rest or of uniform motion. The force required to accelerate a body of mass m is given by ma , where a is the acceleration imparted. There are many kinds of forces, including the gravitational force. The SI unit of force is the newton. See also fundamental forces; field.

Collins Dictionary of Astronomy © Market House Books Ltd, 2006

Force

Anything that changes or tends to change the state of rest of a body; common forces in buildings are the weight of the materials from which they are built, the weight of the contents, and the forces due to wind, snow, and earthquakes.

Illustrated Dictionary of Architecture Copyright © 2012, 2002, 1998 by The McGraw-Hill Companies, Inc. All rights reserved

force

[fȯrs]

(computer science)

To intervene manually in a computer routine and cause the computer to execute a jump instruction.

(mechanics)

That influence on a body which causes it to accelerate; quantitatively it is a vector, equal to the body's time rate of change of momentum.

McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

Force

A dBASE dialect for MS-DOS.

This article is provided by FOLDOC - Free Online Dictionary of Computing (foldoc.org)

Force

(1) See force quit and force touching.

(2) An earlier dBASE compiler developed by Sophco, Inc. that combined C and dBASE structures. Force was noted for generating very small executable programs.

Copyright © 1981-2025 by The Computer Language Company Inc. All Rights reserved. THIS DEFINITION IS FOR PERSONAL USE ONLY. All other reproduction is strictly prohibited without permission from the publisher.

The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Force

 

in mechanics, a quantity that is a measure of the mechanical action on a given physical body by other bodies. This action causes a change in the velocities of points of the body or produces deformation of the body. The action can occur through direct contact—as in friction or the pressures exerted by bodies that are pressed against each other—or through fields generated by the bodies—such as a gravitational field or an electromagnetic field.

A force is a vector quantity and at every moment of time is characterized by a magnitude, direction in space, and point of application. Forces are added according to the parallelogram law. The straight line along which a force is directed is called the line of action of the force. In the case of a nondeformable rigid body, the force can be considered to be applied at any point on its line of action. A force acting on a particle can be constant or variable. The force of gravity is an example of a constant force. A variable force can be dependent on time (for example, an alternating electromagnetic field), the position of the particle in space (a gravitational force), or on the particle’s velocity (the resisting force of the medium).

Forces are measured by static or dynamic methods. The static method is based on the balancing of the force being measured by another, known force (seeDYNAMOMETER). The dynamic method is based on the law of dynamics mw = F. If the mass m of the body is known and the acceleration w of the body’s free translational motion with respect to the inertial frame of reference is measured, the force F can be found from this law. Frequently used units of force are the newton (N) and dyne(dyn): 1 dyn = 10^–5 N, and 1 kilogram-force ≈ 9.81 N.

S. M. TARG

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.