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A gravity-defying science project from Science Buddies

Key Concepts
Physics
Liquids
Geometry
Engineering

Introduction
Can you think of a way to make water run uphill—without using electricity? The ancient Greeks discovered how to do just this! They developed a device called the Archimedes screw to lift water from one location to another. This tool is so useful that it is still in widespread use today. In this activity you will build your own hand-powered Archimedes screw from simple materials.

Background

Archimedes of Syracuse was born in the 3rd century B.C. He liked to solve problems and was one of the most important inventors of his time. The king requested that Archimedes build the biggest ship possible. This ship proved to be leaky, and Archimedes had to invent a device to remove water from it. So he designed what we now call the Archimedes screw. It was very effective because it got rid of the water and only required one person to operate it. The Archimedes screw was soon also used to transport water from low-lying areas up to irrigation ditches. The design is so effective that it is still being used today. For instance, it is used to lift wastewater in water treatment plants and even to lift water in some amusement park rides. It's a tool that has never gone out of style. is a form of positive-displacement pump. A positive-displacement pump traps fluid from a source and then forces the fluid to move to a discharge location. The Archimedes screw is made up of a hollow cylinder and a spiral part (the spiral can be inside, but here you'll put it outside the cylinder). One end is placed in a low-lying fluid source and the other end is tilted up into a higher discharge area. To move water all you need to do is rotate the screw. As the screw moves it scoops up a small amount of water into the first pocket. On the next turn of the screw the first pocket of water moves to the second pocket, and a new scoop of water enters the first pocket. This motion continues, and eventually the first scoop of water comes out at the other end.

There are many factors that determine how well the Archimedes screw will work, such as the length, its angle, the radius and more. In this project you will build and demonstrate your own Archimedes screw. Optionally you can even try changing the screw design to find out how to make it lift water faster!

Materials

• PVC pipe (at least 1 inch in diameter and at least 1 foot long)
• Clear vinyl tubing (at least 1/4 inch diameter and at least 2 feet long; these materials can be found at many hardware stores)
• Duct tape
• Scissors
• Two containers for water
• Two items to elevate one of the containers, such as small boxes or additional containers
• A workspace that can tolerate spills
• An adult helper
• Cloth towel for cleaning up spills (optional)
• Food coloring (optional)
• Different diameters and lengths of PVC pipe (optional)
• Different diameters of vinyl tubing (optional)

Preparation

• Attach one end of the vinyl tubing to one end of the PVC pipe with duct tape. Ensure that the opening to the tubing is open (and not blocked by the tape). 
• Tightly wrap the tubing around the pipe in a spiral.
• Attach the tubing to the other end of the pipe with duct tape, again being careful to not block the opening of the tubing.
• Have an adult help use scissors to cut off any extra tubing.
• If necessary, use extra pieces of duct tape to evenly space out the tubing along the length of the pipe.

Procedure

• Fill one of your containers with water. Optionally, you can add food coloring to make the water easier to see when it is in the tubing.
• Elevate the second (empty) container so it is higher than the first container.
• Place one end of your Archimedes screw in the lower container of water, and align the other end over the upper container.
• Rotate the screw so the bottom end of the tubing "scoops" water with each rotation. It should go underwater and then come back above the surface with each revolution and not remain completely submerged the entire time. If you do not see your tubing start to fill with water after a few rotations, you might be spinning the screw the wrong direction. When you look at your screw from the side, what do you see? How is the water distributed in the tubing?
• Keep rotating the screw, and watch as the water moves up into the higher container!
• Try different ways of using your Archimedes screw. How high can you lift water? Raise the upper container, and tilt the screw upward at a steeper angle. Do you reach a point where water starts to flow back down the tube instead of up?
• Extra: Try different designs of your Archimedes screw. What happens if you change the spacing of the tubing spiral, making the individual turns closer together or farther apart? What if you change the diameter of the PVC pipe or the tubing?

Observations and Results
How does the Archimedes screw manage to move water uphill? When you bend the tubing into a spiral shape, it forms individual pockets where water can get trapped because the tubing curves upward on both sides. If you look at your screw from the side, you will see these pockets filled with water. As you rotate the screw it traps alternating pockets of air and water, and the individual pockets move up the screw to the upper container. If you tilt the screw up at too steep of an angle, eventually one side of each pocket will point downhill allowing the water to flow back down. This is easiest to see if you stand the pipe up vertically—notice how there is nowhere for the water to get "trapped" without flowing downhill.