Question

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

Answer 1

$\text{Speed of water in a river}=2km/hr$

$\therefore \text{Length of flow of water in 1 minute}$

$=\frac{2\times 1000}{60}=\frac{100}{3}m$

$\text{Breadth of river (b)}=40m$

$\text{and depth (h)}=3m$

$\therefore \text{Volume of water}=lbh=\frac{100}{3}\times 40\times 3m^3=4000m^3$

$\text{and volume in litres}=4000\times 1000l$

$(1m^3=1000litres)$

$=4000000litres$