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Wikipedia, In classical mechanics, an impulse is defined as the integral of a force with respect to time. When a force is applied to a rigid body it changes the momentum of that body. A small force applied for a long time can produce the same momentum change as a large force applied briefly, because it is the product of the force and the time for which it is applied that is important. Mathematical derivationwhere
A simple derivation using Newton's second law yields: where
This is often called the impulsemomentum theorem. 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: where
It is often the case that not just one but both of these two quantities vary. In the technical sense, impulse is a physical quantity, not an event or force. The term "impulse" is also used to refer to a fastacting 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. This is a useful model for certain purposes, such as computing the effects of ideal collisions, especially in game physics engines. Impulse has the same units and dimensions as momentum (kg m/s = N·s). Impulse can be calculated using the equation: can be calculated, if initial and final velocities are known, where
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Published  July 2009


