Question

A river 3 m deep and 40 m wide is flowing at the rate of 2 km per hour. How much water (in L) will fall into the sea in a minute?

Answer 1

Given,
Depth of the river (h) = 3 m, Width of the river (w) = 40 m
Flow rate of water = 2 km/hr
i.e. Flow of water in 1 hour = 2 km = 2000 m
Flow of water in 1 minute = 2000/60 = 100/3 m
Thus, length (l) = 100/3 m
Volume of water falling into the sea in 1 minute = Volume of cuboid with dimension l, w, h
$=l\times w\times h=\frac{100}{3}\times 40\times 3=4000m^3=4000\times 1000=4000000L$