Water flow 2

How many litres of water will flow in 7 minutes from a cylindrical pipe 1 cm in diameter, if the water flows at a speed of 30 km per hour

Correct answer:

V =  274.8894 l

Step-by-step explanation:

$$\begin{gathered} t=7\cdot 60=420\text{s} \\ D=1/10=\frac{1}{10}=0.1\text{dm} \\ v=30/3.6\cdot 10=\frac{250}{3}\doteq 83.3333\text{dm/s} \\ s=v\cdot t=83.3333\cdot 420=35000\text{dm} \\ r=D/2=0.1/2=\frac{1}{20}=0.05\text{dm} \\ S=\pi \cdot r^2=3.1416\cdot 0.05^2\doteq 0.0079{\text{dm}}^2 \\ 1d{m}^3=1l \\ V=s\cdot S=35000\cdot 0.0079=274.8894\text{l} \end{gathered}$$

Try another example