A pipe is 3 m wide and 1.2 m deep. The water is flowing with a speed o

1.	A pipe is 3 m wide and 1.2 m deep. The water is flowing with a speed of 20 km/h. How much area will it irrigate in 20 min if 16 cm of water level is desired.
Answer» Speed of the water = 20 km/h = 20000 meter/60 min \(\therefore\) Length of water covered in 20 min = speed x time = \(\frac{20000}{60}\times20=\frac{20000}3\) meter Radius of base of the pipe is r = 3/2 meter \(\therefore\) Volume of water flow = Area of cross section x Length of water flow \(=\pi\times(3/2)^2\times\frac{20000}3\) = 15000 π m³ Standing under depth = 16 cm = \(\frac{16}{100}\) m \(\therefore\) Irrigation area = \(\frac{Volume\,of\,water\,flow}{Standing\,water\,depth}\) \(=\cfrac{15000\pi}{\frac{16}{100}}\)\(=\cfrac{15000\times3.14}{\frac{4}{25}}\) = 294375 m² = 29.43 hactares

A pipe is 3 m wide and 1.2 m deep. The water is flowing with a speed of 20 km/h. How much area will it irrigate in 20 min if 16 cm of water level is desired.

Answer»

Speed of the water = 20 km/h = 20000 meter/60 min

\(\therefore\) Length of water covered in 20 min

= speed x time

= \(\frac{20000}{60}\times20=\frac{20000}3\) meter

Radius of base of the pipe is r = 3/2 meter

\(\therefore\) Volume of water flow = Area of cross section x Length of water flow

\(=\pi\times(3/2)^2\times\frac{20000}3\) = 15000 π m³

Standing under depth = 16 cm = \(\frac{16}{100}\) m

\(\therefore\) Irrigation area = \(\frac{Volume\,of\,water\,flow}{Standing\,water\,depth}\)

\(=\cfrac{15000\pi}{\frac{16}{100}}\)\(=\cfrac{15000\times3.14}{\frac{4}{25}}\)

= 294375 m²

= 29.43 hactares