# Tension (physics)

Tension (physics)

In physics String Tension is the magnitude of the pulling force exerted by a string, cable, chain, or similar object on another object. Tension is measured Newtons (kgm/s2) and is always parallel to the string on which it applies. There are two basic possibilities for systems of objects held by strings."Physics for Scientists and Engineers with Modern Physics", Section 5.7. Seventh Edition, Brooks/Cole Cengage Learning, 2008.] Either acceleration is zero and the system is therefore in equilibrium or there acceleration and therefore a net force is present. Note that a string is assumed to have "negligible mass."

ystem in Equilibrium

A system is in equilibrium when the sum of all forces is zero.

$sum_ \left\{\right\} vec\left\{F\right\} = 0$

For example consider a system consisting of an object that is being lowered vertically by a string with tension, T, at a constant velocity. The system has a constant velocity and is therefore in equilibrium because the tension, in the string (which is pulling up on the object) is equal to the force of gravity, mg, (which is pulling down on the object). (Assume up is positive and down is negative.)

$sum_ \left\{\right\} vec\left\{F\right\} = T - mg = 0$

ystem Under Net Force

A system has a net force when an unbalanced force is exerted on it. An equivalent statement is the sum of all forces is not zero. Acceleration and net force always exist together.

$sum_ \left\{\right\} vec\left\{F\right\} e 0$

For example consider the same system as above but suppose the object is now being lowered with in an increasing velocity downwards (negative acceleration) therefore there exists a net force somewhere in the system. In this case negative acceleration would indicate that | mg | > | T |.

$sum_ \left\{\right\} vec\left\{F\right\} = T - mg e 0$

trings in Modern Physics

String-like objects in relativistic theories, such as the strings used in some models of interactions between quarks, or those used in the modern string theory, also possess tension. These strings are analyzed in terms of their world sheet, and the energy is then typically proportional to the length of the string. As a result, the tension in such strings is independent of the amount of stretching.

References

ee also

* Physical compression
* Force
* Stress
* Tensile strength
* Strings (music)
* Surface Tension

Wikimedia Foundation. 2010.

### Look at other dictionaries:

• Tension — may refer to:In science: *Tension (physics), a force related to the stretching of an object (the opposite of compression) *High tension, in electrical power transmission, wires which carry high voltages *Stress (medicine), also referred to as… …   Wikipedia

• Physics — (Greek: physis φύσις), in everyday terms, is the science of matter [R. P. Feynman, R. B. Leighton, M. Sands (1963), The Feynman Lectures on Physics , ISBN 0 201 02116 1 Hard cover. p.1 1 Feynman begins with the atomic hypothesis.] and its motion …   Wikipedia

• Tension — Ten sion, n. [L. tensio, from tendere, tensum, to stretch: cf. F. tension. See {Tense}, a.] 1. The act of stretching or straining; the state of being stretched or strained to stiffness; the state of being bent strained; as, the tension of the… …   The Collaborative International Dictionary of English

• Tension brace — Tension Ten sion, n. [L. tensio, from tendere, tensum, to stretch: cf. F. tension. See {Tense}, a.] 1. The act of stretching or straining; the state of being stretched or strained to stiffness; the state of being bent strained; as, the tension of …   The Collaborative International Dictionary of English

• Tension member — Tension Ten sion, n. [L. tensio, from tendere, tensum, to stretch: cf. F. tension. See {Tense}, a.] 1. The act of stretching or straining; the state of being stretched or strained to stiffness; the state of being bent strained; as, the tension of …   The Collaborative International Dictionary of English

• Tension rod — Tension Ten sion, n. [L. tensio, from tendere, tensum, to stretch: cf. F. tension. See {Tense}, a.] 1. The act of stretching or straining; the state of being stretched or strained to stiffness; the state of being bent strained; as, the tension of …   The Collaborative International Dictionary of English

• Physics engine — A physics engine is a computer program that simulates Newtonian physics models, using variables such as mass, velocity, friction and wind resistance. It can simulate and predict effects under different conditions that would approximate what… …   Wikipedia

• Tensión superficial — Ejemplo de tensión superficial: una aguja de acero sobre agua. En física se denomina tensión superficial de un líquido a la cantidad de energía necesaria para aumentar su superficie por unidad de área.[1] Esta definición implica que el líqu …   Wikipedia Español

• Surface tension — For the work of fiction, see Surface Tension (short story). Surface tension is a property of the surface of a liquid that causes it to behave as an elastic sheet. It allows insects, such as the water strider (pond skater, UK), to walk on water.… …   Wikipedia

• Vapor tension — Vapor pressure Vapor pressure or Vapor tension Vapor tension . (Physics) The pressure or tension of a confined body of vapor of a chemical substance in equilibrium with the solid or liquid form of the substance. The pressure of a given saturated… …   The Collaborative International Dictionary of English