Force

In physics, a force is an external cause responsible for any change of a physical system. For instance, a person holding a dog by a rope is experiencing the force applied by the rope on his hand, and the cause for its pulling forward is the force exercised by the rope. The kinetic expression of this change is, according to Newton's second law, acceleration, non kinetic expressions such as deformation can also occur. The SI unit for force is the newton.

Types of force

Many forces exist: Coulomb's force (the force between electrical charges), gravitational force (force between masses), magnetic force, frictional forces, centrifugal, impact force, and spring force, to name a few.

Related Topics:
Coulomb's force - Electrical charge - Gravitational force - Mass - Magnetic force - Friction - Centrifugal - Impact force - Spring force

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Only four fundamental forces of nature are known: the strong nuclear force, the electromagnetic force, the weak nuclear force, and the gravitational force. They describe every observable phenomenon. Quantum field theory accurately models the first three fundamental forces, but does not model quantum gravity. Quantum gravity on a large scale can, however, be described by general relativity.

Related Topics:
Fundamental force - Strong nuclear force - Electromagnetic force - Weak nuclear force - Gravitational force - Quantum field theory - Quantum gravity - General relativity

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Forces can also be classified into conservative forces and nonconservative forces. Conservative forces are equivalent to the gradient of a potential, and include gravity, electromagnetic force, and spring force. Nonconservative forces include friction and drag.

Related Topics:
Conservative forces - Gradient - Potential - Gravity - Electromagnetic - Spring - Friction - Drag

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