In physics, a force is any influence that causes an object to undergo a certain change, either concerning its movement, direction, or geometrical construction. It is measured with the SI unit of newtons and represented by the symbol F. In other words, a force is that which can cause an object with mass to change its velocity (which includes to begin moving from a state of rest), i.e., to accelerate, or which can cause a flexible object to deform. Force can also be described by intuitive concepts such as a push or pull. A force has both magnitude and direction, making it a vector quantity.
The original form of Newton's second law states that the net force acting upon an object is equal to the rate at which its momentum changes with time. If the mass of the object is constant, this law implies that the acceleration of an object is directly proportional to the net force acting on the object, is in the direction of the net force, and is inversely proportional the mass of the object. As a formula, this is expressed as:
where the arrows imply a vector quantity possessing both magnitude and direction.
Related concepts to force include: thrust, which increases the velocity of an object; drag, which decreases the velocity of an object; and torque which produces changes in rotational speed of an object. Forces which do not act uniformly on all parts of a body will also cause mechanical stresses, a technical term for influences which cause deformation of matter. While mechanical stress can remain embedded in a solid object, gradually deforming it, mechanical stress in a fluid determines changes in its pressure and volume.
Read more about Force: Development of The Concept, Pre-Newtonian Concepts, Newtonian Mechanics, Descriptions, Fundamental Models, Non-fundamental Forces, Rotations and Torque, Kinematic Integrals, Potential Energy, Units of Measurement
Other articles related to "force":
... with air being deflected by the Coriolis force to create the prevailing westerly winds ... extent of the large scale interaction of pressure gradient force and deflecting force that in the end causes air masses to move along isobars was understood ... By 1912, this deflecting force was named the Coriolis effect ...
... of the imperial crown mounted on a circle featuring the words Royal Australian Air Force, beneath which scroll work displays the Latin motto (shared with the Royal Air Force) Per Ardua Ad ...
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... A fluid flowing past the surface of a body exerts surface force on it ... Lift is the component of this force that is perpendicular to the oncoming flow direction ... It contrasts with the drag force, which is the component of the surface force parallel to the flow direction ...
... The SI unit of force is the newton (symbol N), which is the force required to accelerate a one kilogram mass at a rate of one meter per second squared, or kg·m·s ... The corresponding CGS unit is the dyne, the force required to accelerate a one gram mass by one centimeter per second squared, or g·cm·s−2 ... The gravitational foot-pound-second English unit of force is the pound-force (lbf), defined as the force exerted by gravity on a pound-mass in the standard ...
Famous quotes containing the word force:
“Power acquired by violence is only a usurpation, and lasts only as long as the force of him who commands prevails over that of those who obey.”
—Denis Diderot (17131784)
“Its the old captains dark fate
Who failed to find or force a strait
In its two-thousand-mile coast;
And his crew left him where he failed,
And nothing came of all he sailed.”
—Robert Frost (18741963)
“The example of America must be the example, not merely of peace because it will not fight, but of peace because it is the healing and elevating influence of the world, and strife is not. There is such a thing as a man being too proud to fight. There is such a thing as a nation being so right that it does not need to convince others by force that it is right.”
—Woodrow Wilson (18561924)