Answer
$W\left( v \right) = - 5.4{v^{ - 4}}$
Work Step by Step
$$\eqalign{
& W\left( v \right) = 1.8{v^{ - 3}} \cr
& {\text{Differentiate the function}} \cr
& W\left( v \right) = \frac{d}{{dv}}\left[ {1.8{v^{ - 3}}} \right] \cr
& {\text{Use the constant multiple rule}} \cr
& W\left( v \right) = 1.8\frac{d}{{dv}}\left[ {{v^{ - 3}}} \right] \cr
& {\text{Apply the rule: }}\frac{d}{{dt}}\left[ {{v^n}} \right] = n{v^{n - 1}}{\text{ }} \cr
& W\left( v \right) = 1.8\left( { - 3{v^{ - 4}}} \right) \cr
& W\left( v \right) = - 5.4{v^{ - 4}} \cr} $$
