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Instantaneous Velocity


$\displaystyle\vec{v}$ = $\displaystyle\lim_{\Delta t \rightarrow 0}^{}$$\displaystyle{\frac{\Delta \vec{r}}{\Delta t}}$

Figure 3.3: Instantaneous velocity in 2-D.
\epsfysize=8 cm

Interpretation: When $\Delta$t $\rightarrow$ 0, the point Q in the figure gets closer and closer to the point P and the direction of $\Delta$$\vec{r}$ approaches the direction of a tangent to the curve at point P. Thus the instantaneous velocity $\vec{v}$ is parallel to the tangent and in the same direction as the motion.