#### Answer

$$ \frac{ \sqrt { 21 \pi v}}{7 \pi}$$

#### Work Step by Step

$$ \sqrt { \frac{3v} {7 \pi}}$$
We rationalize the denominator:
$$ \sqrt { \frac{3v} {7 \pi}} \times \sqrt { \frac{7 \pi} {7 \pi}}$$
This gives:
$$ \frac{ \sqrt { 3v*7 \pi}}{7 \pi}$$
$$ \frac{ \sqrt { 21 \pi v}}{7 \pi}$$