Question

A cuboidal water tank measuring 80 cm × 60 cm × 60 cm is filled from a pipe of cross sectional area 1.5 $c{m}^2$. If speed of water is 3.2 m/s, then how long does it take to fill the tank?

• A. 5 mins
• B. 10 mins
• C. 12 mins
• D. 15 mins

Answer 1

The correct option is B

10 mins

Given that the tank is cuboidal.
We know, volume of a cuboid of dimensions l×b×h is lbh.
Hence, volume of water tank = (80 x 60 x 60) $c{m}^3$
Given, area of cross section = 1.5 $c{m}^2$
and speed of water = 3.2 m/s = 320 cm/s

Therefore, volume of water flowing in one second
= area of cross section × speed of water
= 1.5 x 320
= 15 x 32 $c{m}^3$

$\therefore$ Time taken to fill the entire tank
$=\frac{60\times 60\times 80}{15\times 32}=600\text{seconds}=10\text{mins}$