Mathematics

Problem

The position of a particle moving in space is given by the vector-valued function

\mathbf r(t)

. Which expression gives the particle’s speed at time

t

? a)

|\mathbf r(t)|

\displaystyle\frac{d}{dt}|\mathbf r(t)|

|\mathbf r'(t)|

|\mathbf r'(t)|^{2}