N1L: no force $\Rightarrow \vec{V}={\rm const}$ (or at rest, $\vec{V}=0$) implies existence of inertial reference frames

N2L: \[ \vec{a}={1\over m}\vec{F}_{\rm total}, \quad \mbox{or} \quad \sum \vec{F}= m \vec{a} \] implies that objects have mass, a measure of inertia

N3L: all forces are due to interactions \[ \vec{F}_{\rm A\> on\> B} = - \vec{F}_{\rm B \> on \> A} \]

1. read and re-read; itentify what is known/unknown
2. make a drawing, or
   draw a vector diagram, identify all [pairs of] forces
3. use the laws of Physics to establish formal relationships ($F=ma$), or
   use N2L to determine acceleration, $\vec{a}={1\over m}\vec{F}_{\mbox{total}}$
4. perform algebraic manipulations to get the final result, or
   use kinematics, i.e. $\vec{a} \rightarrow \vec{V} \rightarrow \vec{r}$
5. substitute numerical values; watch significant figures
6. check units; does the result make sense?