Question

How many litres of water flow out through a pipe of cross sectional area $9\pi {cm}^2$ in one minute, if speed of water in pipe is $40cm/sec$.

• A. $21600\pi l$
• B. $260\pi l$
• C. $21.6\pi l$
• D. None

Answer 1

Answer: (C)

$21.6\pi l$

Cross-sectional area $=$ $9\pi {cm}^2$

Speed of water $=40cm/sec$

Volume of water flown in $1$ sec $=9\pi \times 40=360\pi {cm}^3$

$\therefore$ Volume of water flown in $1$ min $=60\times 360\pi =21600\pi {cm}^3$

Now $\Rightarrow 21600\pi {cm}^3\Rightarrow \frac{21600\pi }{1000}litre=21.6\pi$ litres