Question

A rectangular Reservoir is 120 M long and 75 M wide at what speed per hour must water flow into it through a square pipe of 20 cm wide shoulder the water rises by 2.4 metre in 18 hours?

Answer 1

Length of the reservoir = 120 m
Breadth of the reservoir = 75 m
The height of the water level in 18 hours = 2.4 m
Volume of the water collected in the reservoir = 120 × 75 × 2.4                                                                         = 21600 m³
Let the speed of the flowing water = x m/hr
The water flowing in the pipe forms a cuboid of width 20 cm or 0.2 m and
height of 20 cm or 0.2 m.
The length of the cuboid so formed in the pipe in 18 hours = 18x m
Therefore,
the volume of the water flows out of the pipe in 18 hours = 0.2 × 0.2 × 18x                                                                                                              = 0.72x m³
Therefore,
Volume of the water collected in the reservoir = volume of the water flows out of the                                                                                                         pipe in 18 hours.
21600 = 0.72x
x = 21600/0.72
x = 30000 m/hr
speed of the water = 30 km/hr


:)(: Hope This Helps !!!! :)(:

Answer 2

Volume of water delivered in 18h=120m*75m*2.4m
=21600 cubic meter(cu.m)
Volume of water delivered in 1h=21600 cu.m/18
= 1200 cu.m
Therefore volume of water delivered by the pipe in 1h=1200 cu.m=l*b*h
1200 cu.m=0.2m*0.2m*h
h=1200 cu.m/0.04 sq.m
h=30000m=30km
Speed of water delivering pipe =30km/h
I hope it may help you.