# Is the Newton the unit for impulse?

May 2, 2014

The standard unit for impulse is the Newton-second. ($N \cdot s$, or equivalently, $k g \cdot \frac{m}{s}$) This is the same unit that is typically used to measure momentum.

We can see why this is true by taking a look at what types of units are used in the formulas for impulse:

$J = {F}_{a v g} \cdot \Delta t$
$J = \Delta p$

In the first formula, the average force, measured in Newtons, is multiplied by the change in time, which is measured in seconds. Thus, the result will be in Newton-seconds because we are multiplying Newtons by seconds.

The second formula will agree. Since it can be viewed equally as $J = {p}_{2} - {p}_{1}$, the unit for impulse must be the same as the unit for momentum. When two numbers with the same units are added or subtracted, the result will always have the same unit.