Question

Water flows through a cylindrical pipe of internal diameter 7 cm at 2 m per second. If the pipe is always half full, then what volume of water (in litres) can be discharged in 10 minutes?

• A. 2310
• B. 3850
• C. 4620
• D. 9240
• E. 8260

Answer 1

The correct option is C ($4620$)

Since, volume of pipe filled is constant, so inflow rate = outflow rate.

Volume of water flown in 1 second = $\left(\frac{22}{7}\times \frac{7}{2}\times \frac{7}{2}\times 200\right)$cm${}^3$= $7700cm$${}^3$
[Since, volume of cylinder $\pi r^{2}h$

Volume of water flown in 10 minutes = (7700 $\times$ 60 $\times$10) $cm$${}^3$

= $\left(\frac{7700\times 60\times 10}{1000}\right)$ litres [Since, $1$ litres$=1000c{m}^3$]

=$4620$ litres