Question 21 (Or 1st) - CBSE Class 10 Sample Paper for 2019 Boards

Last updated at Nov. 30, 2018 by Teachoo

Question 21 (OR 1
st
question)

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

Question 21 (OR 1st question)
Water is flowing at the rate of 15 km per hour through a pipe of diameter 14cm into a rectangular tank which is 50 m long and 44 m wide. Find the time in which the level of water in the tank will rise by 21 cm.
Let length of pipe for filling whole tank be h m.
So, Volume of pipe = Volume of tank
Volume of pipe
Pipe is in form of cylinder where
Let Height = h m
Diameter = 14 cm
So, radius = ๐ท๐๐๐๐๐ก๐๐/2 = 14/2 = 7 cm
= 7/100 m
Volume of pipe = Volume of cylinder
= ๐r2h
= ๐(7/100)^2 h
= 22/7 ร 7/100 ร 7/100 ร h = (22 ร 7)/10000h
Volume of tank
Tank is in form cuboid where
Length = l = 50 m
Breadth = b = 44 m
Height = h = 21 cm = 21/100 m
Volume of tank = lbh
= 50 ร 44 ร 21/100
= (44\ ร 21)/2
= 22 ร 21
Now,
Volume of pipe = Volume of tank
(22 ร 7)/10000h = 22 ร 21
h = (22 ร 21 ร 10000)/(22 ร 7)
h = 30,000 m
h = 30 km
Now,
Water in pipe flows at rate 15 km/hr
So,
15 km travels in pipe in = 1 hour
1 km travels in pipe in = 1/15 hour
30 km travels in pipe in = 30/15 hour
= 2 hours
So, in 2 hours, the tank will be filled

Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 9 years. He provides courses for Maths and Science at Teachoo.