# Equation of Continuity-Three Fire Hoses and Pipes

1. Jun 7, 2012

### varyvod001

Equation of Continuity--Three Fire Hoses and Pipes

1. The problem statement, all variables and given/known data

Three fire hoses are connected to a fire hydrant. Each has a radius of 0.020 m. Water enters the hydrant through an underground pipe of radius 0.080 m. In the pipe the water has a speed of 3.0 m/s. How many kilograms of water are poured onto the fire in one hour? What's the water speed in each hose?

2. Relevant equations

A1 x V1 = A2 x V2
m = V x rho
I'm not really sure what other equations are relevant.

3. The attempt at a solution

I don't even know where to start. I need the volume...I think, and I'm very confused.

2. Jun 8, 2012

### LawrenceC

Re: Equation of Continuity--Three Fire Hoses and Pipes

You know the velocity of the water in the pipe feeding the hydrant. You have the formula for the volumetric flow in a pipe which is Q=A*V. What are the units of the equation? A formula for mass flow is m=rho*Q. And lastly, what enters the hydrant exits the hydrant assuming all the exits are being used. That is what is meant by 'continuity'.