Question

Question No. 31
Water flows through a pipe of cross section 20 cm with the speed of 6 km/hr to imigate a land Find how much area can irrigated in 20 minute if the land needs only 2 cm of standing water for irrigation.
200 m
300 m-​

Answer 1

Diameter of cross section = 20cm
Radius of cross section = 20/2 = 10cm= 0.1m
Speed = 6 km / h = 6*1000m/ 1* 60min
= 6000/60 m/min
= 100 m/ min
Volume of water flow in field per min= ares of cross section * speed
= 3.14* 0.1*0.1 * 100
= 314 cube meter per minutes
So,
Volume of water in 20 min = 314* 20
= 6280
= 6280 cube meter
Vol. of water in field = vol of water flow by pipe
Area of field * height = 6280
Area of field * 2/100 = 6280
Area of field = 628000/2 = 314000 sq.m