Question

Water is flowing at the rate of $15km$ per hour through a pipe of diameter $14cm$ into a rectangular tank which is $50m$ long and $44m$ wide. Find the time in which the level of water in the tank will rise by $21cm$

Answer 1

Speed of water $=15km/h$

$=15\times \frac{1000}{3600}$

$=\frac{15\times 10}{36}=\frac{25}{6}m/h$

Diameter =$14cm$

$2r=14$

$r=7$

the area of pipe $=\pi r^2$

$=\frac{22}{7}\times 7\times 7$

$=154cm=\frac{154}{100\times 100}$

$\Rightarrow \frac{25}{6}\times \frac{154}{1000}$

area of rectangle

$50\times 44=2200$

$\Rightarrow 2200\times \frac{21}{100}=\frac{25}{6}\times \frac{154}{1000}\times t$

$t=\frac{2200\times 21\times 6\times 10000}{25\times 154\times 100}$

$t=100\times 18\times 4$

$t=\frac{7200}{3600}$

$t=2hrs$