# A river 3 m deep and 40 m wide is flowing at the rate of 2 km per hour. How much water will fall into the sea in a minute?

**Solution:**

Given: the depth and width of the river are 3 m and 40 m respectively and water is flowing at the rate of 2 km per hour.

We have to find the amount of water that will fall into the sea in a minute.

Since the water in the river flowing in a cuboidal shape and the volume of the water that falls into the sea is nothing but the volume of the cuboid.

The volume of the cuboid of length l, breadth b, and height h, = lbh

Water is flowing at the rate of 2 km per hour, but we need to change this into meters per minute so that we can obtain the length of the flowing water in a minute.

Hence, we can easily find the volume of water that falls into the sea by calculating the volume of the cuboid.

Width of the river, b = 40 m

Depth of the river, h = 3 m

Flowing rate of water = 2 km / h

= 2000 m / 60 min

= 100/3 m/min

Length of the water flowing in 1 minute, l = 100/3 m

The volume of the water that falls into the sea in 1 minute = l × b × h

= 100/3 m × 40 m × 3 m

= 4000 m^{3}

Thus, 4000 m^{3} of water will fall into the sea in a minute

**Video Solution:**

## A river 3 m deep and 40 m wide is flowing at the rate of 2 km per hour. How much water will fall into the sea in a minute?

### Class 9 Maths NCERT Solutions - Chapter 13 Exercise 13.5 Question 9:

**Summary:**

It is given that there is a river 3 m deep and 40 m wide which is flowing at the rate of 2 km per hour. We have found that 4000 m^{3} of water will fall into the sea in a minute