A cylindrical water tank of diameter 1.4m and height 2.1m is being fed by a pipe of diameter 3.5cm through which water flows at the rate of 2 metre per second. In how much time the tank will be filled?

Answer

28 minutes

Explanation

Volume of water tank `= {pi xx (0.7)^(2) xx 2.1} m^(2) = ((1029pi)/(1000)) m^(2)`
Volume of water that flows through the pipe in 1s
`= (pi xx (3.5)/(200) xx (3.5)/(200) xx 2)m^(3) = ((49pi)/(80000))m^(3)`
Let the tank be filled in x seconds. Then,
`(49pi)/(80000) xx x = (1029pi)/(1000) rArr x = ((1029 xx80)/(49))` seconds
`= 1680s = 28` min