Exercise 16

If $\vu \times \vw = \vzero$, what does this say about the direction of $\vu$ and $\vw$?

Remember that the vector $\vv$ has magnitude and direction, so the derivative $\frac{d\vv}{dt} = \va$ will measure the change in both the magnitude and direction of of $\vv$. Write a few sentences to describe how if $\vv$ and $\va= \frac{d\vv}{dt}$ are in parallel directions, then the unit normal vector will be undefined at that point.