My science fair was about Bernoulli’s Principle. My propose was “Will changing the velocity of water movement through the pipe cause the pressure to increase or decrease?”. So I would make a Bernoulli Apparatus, And then when the water ran through, depending on the sizes of the pipe through out the Apparatus will speed up the water and then cause the pressure to go high or low. Bernoulli’s Principle says that as the speed increases, the pressure will decrease. So as the water when through the narrow pipe, the water speed up,causing the presser to go down. The water broad, clear  plastic pipes zip tied on to a peg broad, show the pressure ( higher up, higher pressure, lower up, lower pressure).

This is what I did, how to do this experiment, and the after word.

• Purpose:

Will changing the velocity of water movement through the pipe cause the pressure to increase or decrease?

• Research:

Bernoulli’s Principle says that when a fluid is traveling in a horizontal direction, as the velocity increases the will decrease and vice versa. The principle shows when the pressure is at it’s lowest, and is at it’s highest.  Some of the things that use Bernoulli’s Principle are race cars, airplanes (Bernoulli’s Principle makes it possible to fly), and it helps a baseball player throw a curveball. The fluids increase speed, when pushed through a narrower space, will cause internal pressure to decrease even though it is in a tighter space.  The external pressure increase at slower speeds.  Streamlines are invisible lines that are used to represent the paths in which particles are moving. Liquids and gases are both fluids but solids are not. Bernoulli’s Principle powers the airfoil because of the low air pressure and high speed pushes the wings up and keeps them there becuase of the pressure difference on the top and bottom.This is expressed as Bernoulli’s Equation. The more fundamental job that Bernoulli’s Principle shows is the conservation of energy. This principle helps an object move from potential energy to kinetic energy. Bernoulli was one of the first scientist to express kinetic theory of gases. Most experiments of that time where the way water and other liquids fluids when through pipes

• Hypothesis:

Bernoulli’s Principle states that as the pipe widens the velocity will decrease and cause the pressure to increase. When the pipe narrows the velocity increases and will cause a decrease in the pressure. So I think that the wider pipes will rise the highest because the water will be traveling at a lower speed and then cause the pressure to be higher.

• Experiment

Material & Supplies:

• Waterproof Glue

• Pegboard

• 6 sections of clear Plastic Tubing (approximately 3 feet long each)

• 5 Different Sized Sections of Plastic PVC Pipe (each with a different Diameter) you will need two sections of your 48 mm pipe

A – 48 mm

B – 42 mm

C – 40 mm

D – 33 mm

E – 21 mm

F – 15 mm

• 6 Tap Connectors – connecting the PVC Pipe and the plastic tubing

• 5 Gallon Bucket (we used a Lowe’s bucket)

• Water

• Zip Ties to fasten the pipes

• Food Coloring (optional)

• Large clear plastic tubing cut into two long and 1 short Pieces

• Water Pump (must have a waterproof cord)

• Outlet or Power Source

• Valve

• Ruler / tape measure

• Step-By-Step:

1. Gather all of your supplies. For this next step you will need the six pipe sections, a drill, taps, and waterproof glue

2. Glue all of the pipe sections together with the waterproof glue.  Start with the 48 mm wide pipe glue that to the that one to the 42.3 mm pipe then you glue the42.3 to the 40.6 mm pipe and so on. [These are the pipes you need to glue on in order. 48.45, 42.3, 40.6, 33.65, 21.46, and other 48.45 to show that the process really does use Bernoulli’s Principle (this one will be a little bit less than the first 48.45 because of back pressure.)]  Wait 30 minutes until the glue drys and drill holes in each section of the pipe. Put one tap in each hole and glue tell scure.

3. Attach the plastic tubing to each one of the taps and glue them on with waterproof glue.

4. Wait another 30 minutes for glue to dry. While you are waiting you can do the next steps.

5. Take  your clear plastic tubes and put them on the pegboard.

6. Zip tie your 6 plastic tubes to the peg board (make sure that some ends are sticking up)

7. When the glue has dried, hook the taps to the clear plastic pipes.

8. Thread a large tap on each side of the Bernoulli Apparatus. They need to be the same size as the  mm pipes because this where you will put them.

9. Now connect one end the mm long pipe to the Bernoulli Apparatus and the other side to the valve. Gule around both sides to stop any leaks.

10. To the other side of the valve, put in one of the   mm pipes.This will be your input pipe

11. In the other hole in the Bernoulli Apparatus put the other   mm pipe.

12. Connect the two pipes together with a zip tie.

13. Fill up your 5- gallon bucket all the way.

14. Attach the pump to the input pipe (left pipe).

15. Put the pump and the two mm pipes in the water with only with the pump’s cord sticking out and connect that to the extension cord (if needed) to the power source.

16. Dye the water if needed (makes the water easier to see)

17. Turn the valve to different positions and watch as the water move along the board because of the different pressures.

• Constants:  

The constant is the assembled pipe (Bernoulli Apparatus) because it stays the same size, length, and order throughout the whole experiment.

• Manipulated Variable:

We changed the amount of water going through the pipe to see how the higher amount of water affected the speed and pressure.

• Responding Variable:

Due to the velocity of the water traveling through the narrowing pipe the pipe the pressure will decrease or increase resulting in the water moving higher or lower in the tubing. This is seen by the water going up the Small clear plastic tubes because of the amount of pressure at that location.  Then we could measure the high of the water using a ruler and then graphed that to find out the percentage of the pressure.

• Analysis:

When we were watching the experiment we noticed that every time that pipe number 5 always had a lower pressure than pipes number 1-4 or 6. The reason was because that with a thinner pipe the speed increased causing less pressure and the water to not rise very high on the Bernoulli Apparatus. Pipe 6 was not as high as pipe 1 even though the water was traveling at the same a speed because pipes 1-4 were also affected by the back pressure from the narrower pipe.

• Conclusion: 

My hypothesis was correct because as the water moved into wider spaces, it slowed down and the pressure rose.  The water registered the highest when it was flowing through the thickest pipe.  The results of the experiment confirmed that Bernoulli’s Principle is true and was reflected in the results of the Bernoulli Apparatus that contains various diameters of pipes.  When the speed of the water increases the pressure of the water decreases.  The experiment also confirmed that pipe two had the highest pressure (it was the second largest).  The smallest pipe (number five) had the least amount of pressure because the water was flowing through it fastest then it was through any of the other pipes.   In the future I would like to test back pressure because though pipe number six and pipe number were the same diameter and the water was going through at the same speed they were not consistently the same because of the back pressure.  I would like to try a similar experiment instead of using stair steps I would like to a cone shaped pipe to try and eliminate back pressure in the experiment.