Question

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

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

Answer 1

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

$\begin{array}{c}Diameter=8\times {10}^{-3}m\\ V=0.4m/s\\ v=\sqrt{u^2+2gh}]\\ =\sqrt{{\left(0.4\right)}^2+2\times 10\times 0.2}\\ =2m/s\\ A_1{v}_1=A_2{v}_2\\ \pi {\left(\frac{8\times {10}^{-3}}{4}\right)}^2\times 0.4=\pi \times \frac{d^2}{4}\times 2\\ d\approx 3.6\times {10}^{-3}m\end{array}$

Hence, Option $C$ is correct.