$\text { Find the velocity vector in terms of } u _ { r } \text { and } u _ { \theta } \text {. }$

question 73

Multiple Choice

$\text { Find the velocity vector in terms of } u _ { r } \text { and } u _ { \theta } \text {. }$
- $r = 2 \cos 2 t$ and $\theta = 4 t$

• A) \(\mathbf { v } = ( - 8 \sin 4 \mathrm { t } ) \mathbf { u } _ { \mathrm { r } } + 4 \cos 4 \mathrm { tu } _ { \theta }\)
• B) \(\mathbf { v } = ( 4 \sin 2 \mathrm { t } ) \mathbf { u } _ { \mathrm { r } } + 8 \cos 2 \mathrm { tu } _ { \theta }\)
• C) \(\mathbf { v } = ( - 4 \sin 2 \mathrm { t } ) \mathrm { u } _ { \mathrm { r } } + 8 \cos 2 \mathrm { tu } _ { \theta }\)
• D) \(v = ( - 2 \sin 2 t ) u _ { r } + 8 \cos 2 t u _ { \theta }\)