Impulse

From Free net encyclopedia

This article is about the physical quantity of impulse. For other meanings of the term please see Impulse (disambiguation)

In classical mechanics, the impulse of a force is the product of the force and the time during which it acts. Although momentum is conserved within a closed system, individual parts of a system can undergo changes in momentum. Impulse has the same units and dimensions as momentum (kg m/s or N-s). The impulse of a time-varying force is calculated as the integral of force with respect to time:

<math>\mathbf{I} = \int \mathbf{F}\, dt </math>

where

I is impulse,

F is the force,

t is an infintesimal amount of time.

In the presence of a constant net force, impulse is equal to the average impulse:

<math>\mathbf{I} = m \Delta \mathbf{v} = \mathbf{F}\Delta t </math>

where

m is the mass of the object,

Δv is the change in velocity,

F is the constant net force applied (in order to change the velocity), and

<math>\Delta t</math> is the time interval over which the force is applied.

Using the definition of force yields:

<math>\mathbf{I} = \int \frac{d\mathbf{p}}{dt}\, dt </math>

<math>\mathbf{I} = \int d\mathbf{p} </math>

<math>\mathbf{I} = \Delta \mathbf{p} </math>

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 change in an object's momentum caused by a fast-acting force. This type of impulse is often idealized so that the change in momentum 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 computations, such as computing the effects of ideal collisions, especially in game physics engines.

[edit]

Impulse

From Free net encyclopedia

See also

Views

Personal tools

Search

Partner sites