A water main with a radius of 0.15 m contains water with an average velocity of 3 m/s .What is the flow rate in the water main?

To calculate the flow rate in the water main, we need to use the formula:

Flow rate = Area x Velocity

1. First, we need to find the area of the water main. The water main is assumed to have a circular cross-section, so the area can be found using the formula for the area of a circle:

Area = π x (radius)^2

In this case, the radius of the water main is given as 0.15 m, so we can substitute it into the formula to get:

Area = π x (0.15)^2

2. Next, we need to find the average velocity of the water flowing through the water main. It is given as 3 m/s.

3. Now that we have the values for the area (step 1) and the velocity (step 2), we can calculate the flow rate using the formula:

Flow rate = Area x Velocity

Substituting the values we have:

Flow rate = π x (0.15)^2 x 3

Now, we can simplify this expression by calculating the values inside the parentheses and multiplying by π and 3:

Flow rate = 0.0707 x 3

Flow rate = 0.2121

Therefore, the flow rate in the water main is 0.2121 m^3/s.