# Solve Pressure and Velocity of 4" to 2" Hose Problem

• jlcowgill
In summary, the conversation discusses the use of a 4" hose with a 2" nozzle, a resistance coefficient of .12, and a water jet velocity of 24.4 m/sec. The question at hand is how to find Pressure 1 and velocity 1. To solve this, the continuity equation can be used to calculate the upstream velocity, and then Bernoulli's equation can be used to calculate the upstream pressure. The speaker was on the right track and thanks the person named Joe for their help.
jlcowgill
I have a 4" hose attached to a 2" nozzle, me resistance coeffient of the nozzle is .12, and the jet of water exiting the nozzle is 24.4 m/sec. The water is flowing from the 4" to the 2". What I am having trouble finding is Pressure 1 and the the velocity 1.

What I know is that P2=0, areas of the hose is 4" = 12.56 in^2 converts to .008m^2, 2" = 3.14 in^2 converts to .002m^2, I think Q=V2*A2 = 24.4*.002= .049 m^3/sec

then v1= 6.125 m/s?
then would I plug this into the bernoulli's equ.??

Thank You

Use the continuity equation to calculate the upstream velocity. If you know the velocity at the downstream loacation, this would equate to a certain mass flow rate. The mass flow rate will remain constant. So, since this is water and density can be considered constant, you have the old area, the density and the only unknown would be the velocity.

For the second part, once you have the upstream velocity, you can use Bernoulli to calculate the upstream pressure.

I was basically on the right track

thank you
Joe

## 1. What is the formula for calculating pressure and velocity in a hose problem?

The formula for calculating pressure and velocity in a hose problem is P = (4Q)/πr2 and V = Q/πr2, where P is pressure, Q is flow rate, and r is the radius of the hose.

## 2. How do I determine the flow rate in a hose problem?

The flow rate in a hose problem can be determined by measuring the amount of fluid passing through the hose in a given time period. This can be done using a flow meter or by collecting the fluid in a known volume container and measuring the time it takes to fill.

## 3. What units should I use to measure pressure and velocity in a hose problem?

Pressure is typically measured in units of pounds per square inch (psi) or pascals (Pa), while velocity is measured in units of feet per second (ft/s) or meters per second (m/s). It is important to use consistent units for accurate calculations.

## 4. How do I convert between different units of pressure and velocity?

To convert between different units of pressure, you can use conversion factors such as 1 psi = 6894.76 Pa. Similarly, to convert between units of velocity, you can use conversion factors such as 1 ft/s = 0.3048 m/s. It is important to use the correct conversion factors to ensure accurate calculations.

## 5. What factors can affect the pressure and velocity in a hose problem?

The pressure and velocity in a hose problem can be affected by factors such as the diameter and length of the hose, the viscosity of the fluid, and any obstructions or bends in the hose. Changes in these factors can alter the flow rate and ultimately impact the pressure and velocity in the hose.

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