Deriving the

Impulse-Momentum Equation -

An Alternate Method

BHS -> Mr. Stanbrough -> -> Physics -> Mechanics -> Momentum -> Impulse & Momentum -> this page

Suppose you apply a constant net force, Fnet, to an object of mass m. Newton's Second Law tells you that the object will accelerate, so if it starts with velocity vo, after some time t its velocity will be v. This situation is diagrammed below.

Situation diagram

From kinematics we know that the acceleration of the object is the rate its velocity changes. In symbols:

a = delta v over t

We also know, from Newton's Second Law, that:


Setting the right sides of these equations equal to each other gives:

Fnet/m = delta_v/t


Fnet t = m delta_v

This is the Impulse-Momentum Equation.

last update January 12, 2010 by JL Stanbrough