Question

A lock in a canal is 40m long , 7m wide. When the sluices are opened, the depth of water in the lock decreases from 5m to 3m 80cm. How many metres of water runs out ?

Answer 1

Length of lock,l=40m

Breadth of lock,b=7m

Height of water in lock,h=5m

So, Volume=lbh=40×7×5=1400m3

Volume of lock when level of water decrease from 5m to 3m 80cm=3.8m=40×7×3.8=1064m3

So,

water runs out from lock=1400-1064m3=336m3

Answer 2

Given that,

Length of a canal, l = 40 m

Breadth of a canal, b = 7 m

Depth of water, h = 5 m

To find,

When the depth of water in the lock decreases from 5m to 3m 80 cm, how many metres of water runs out.

Solution,

Initial volume of lock is given by :

$V=lbh\\\\V=40\times 7\times 5=1400\ m^3$

When the depth is from 5m to 3m 80 cm, new height becomes, 3.8 m. New volume of the lock is :

$V'=40\times 7\times 3.8=1064\ m^3$

Difference in volume,

V = 1400 m³- 1064 m³

V = 336 m³

So, 336 m³ of water runs out for the slices. Hence, this is the required solution.