In classical mechanics, an impulse is defined as the integral of a force with respect to time: Look up impulse in Wiktionary, the free dictionary. ... Classical mechanics (commonly confused with Newtonian mechanics, which is a subfield thereof) is used for describing the motion of macroscopic objects, from projectiles to parts of machinery, as well as astronomical objects, such as spacecraft, planets, stars, and galaxies. ... This article is about the concept of integrals in calculus. ... For other uses, see Force (disambiguation). ... Look up time in Wiktionary, the free dictionary. ...

where

I is impulse (sometimes marked J),

F is the force, and

dt is an infinitesimal amount of time.

A simple derivation using Newton's second law yields: Infinitesimals have been used to express the idea of objects so small that there is no way to see them or to measure them. ... Newtons laws of motion are the three scientific laws which Isaac Newton discovered concerning the behaviour of moving bodies. ...

As a result, an impulse may also be regarded as the change in momentum of an object to which a force is applied. The impulse may be expressed in a simpler form when both the force and the mass are constant: This article is about momentum in physics. ...

where

F is the constant total net force applied,

Δt is the time interval over which the force is applied,

m is the constant mass of the object,

Δv is the change in velocity produced by the force in the considered time interval, and

mΔv = Δ(mv) is the change in linear momentum.

However, it is often the case that one or both of these two quantities vary.

In the technical sense, impulse is a physical quantity, not an event or force. However, the term "impulse" is also used to refer to a fast-acting force. This type of impulse is often idealized so that the change in momentum produced by the force happens with no change in time. This sort of change is a step change, and is not physically possible. However, this is a useful model for certain purposes, such as computing the effects of ideal collisions, especially in game physics engines. In mathematics, a function on the real numbers is called a step function if it can be written as a finite linear combination of indicator functions of half-open intervals. ... A physics engine is a computer program that simulates Newtonian physics models, using variables such as mass, velocity, friction and wind resistance. ...

Impulse has the same units and dimensions as momentum (kg m/s = N·s). “Kg” redirects here. ... Metre per second (U.S. spelling: meter per second) is an SI derived unit of both speed (scalar) and velocity (vector), defined by distance in metres divided by time in seconds. ... For other uses, see Newton (disambiguation). ... This article is about the unit of time. ...

See also

• specific impulse
• Wave-particle duality defines an impulse for waves. The preservation of momentum at a collision is then called phase matching. Applications include:
  • Compton effect
  • nonlinear optics
  • Acousto-optic modulator
  • Umklapp scattering
  • electron phonon scattering

Specific impulse (usually abbreviated Isp) is a way to describe the efficiency of rocket and jet engines. ... In physics, wave-particle duality holds that light and matter exhibit properties of both waves and of particles. ... Nonlinear optics is the branch of optics that describes the behaviour of light in nonlinear media, that is, media in which the polarization P responds nonlinearly to the electric field E of the light. ... The Compton Effect is the second album from rapper Greydon Square. ... Nonlinear optics is the branch of optics that describes the behaviour of light in nonlinear media, that is, media in which the polarization P responds nonlinearly to the electric field E of the light. ... An acousto-optic modulator (AOM) consists of a piezo-electric transducer which creates sound waves in a material like glass or quartz. ... Umklapp scattering (also U-Process or Umklapp process) is an anharmonic phonon-phonon (or electron-phonon) scattering process creating a third phonon with a k-vector outside the first Brillouin zone. ... Normal modes of vibration progression through a crystal. ...

References

• Serway, Raymond A.; Jewett, John W. (2004). Physics for Scientists and Engineers, 6th ed., Brooks/Cole. ISBN 0-534-40842-7. 
• Tipler, Paul (2004). Physics for Scientists and Engineers: Mechanics, Oscillations and Waves, Thermodynamics, 5th ed., W. H. Freeman. ISBN 0-7167-0809-4. 

External links and references

• Dynamics