# Question #593cb

Oct 12, 2015

Force $\left(\vec{F}\right)$is a push or a pull and is measured in Newtons (N)

Impulse $\left(\vec{I}\right)$gives a measure of how long the force acts on the objects and is equal to the change in momentum brought about.
Its units is hence either $N . s \mathmr{and} k g . m / s$

From Newton's 2nd Law of Motion, the resultant force acting on an objects is equal tot he rate of change of momentum brought about, ie
$\sum \vec{F} = \frac{\mathrm{dv} e c p}{\mathrm{dt}} = \frac{d}{\mathrm{dt}} \left(m \vec{v}\right)$
Hence $\vec{F} \mathrm{dt} = \vec{I} = m d \vec{v}$

Oct 12, 2015

Consider a force $F \left(t\right)$ not constant but function of time such as the one experienced by an object (tennis ball) during an impact:
The force varies rapidly between two instants ${t}_{1}$ and ${t}_{2}$ so that:
where ${F}_{m}$ is the mean value of the force so that the grey square area is equal to the red total area under the original curve.