Home > Courses > 1P21_Sternin > Dynamics Newton's Laws 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 $\vec{F}_{\rm A\> on\> B} = - \vec{F}_{\rm B \> on \> A}$ Problem-solving strategy, refined read and re-read; itentify what is known/unknown make a drawing, or draw a vector diagram, identify all [pairs of] forces use the laws of Physics to establish formal relationships ($F=ma$), or use N2L to determine acceleration, $\vec{a}={1\over m}\vec{F}_{\mbox{total}}$ perform algebraic manipulations to get the final result, or use kinematics, i.e. $\vec{a} \rightarrow \vec{V} \rightarrow \vec{r}$ substitute numerical values; watch significant figures check units; does the result make sense?