Question

Water is flowing continuously from a tap having an internal diameter $8\times {10}^{-3}m$. The water velocity as it leaves the tap is $0.4m{s}^{-1}$. The diameter of the water stream at a distance $2\times {10}^{-1}m$ below the tap is close to

• A. $5.0\times {10}^{-3}m$
• B. $7.5\times {10}^{-3}m$
• C. $9.6\times {10}^{-3}m$
• D. $3.6\times {10}^{-3}m$.

Answer 1

The correct option is D $3.6\times {10}^{-3}m$.

$A_1{v}_1\left(top\right)=A_2{v}_2\left(bottom\right)$
$v_2^2=v_1^2+2gh$
$v_2^2={0.4}^2+2\times 9.8\times 0.2$
$v=2m{s}^{-1}nearly$
$\pi [8\times {10}^{-3}]\times 0.4=\pi d^2\times 4$
$d=3.6\times {10}^{-3}m$