Summary
Introduction
The Archimedes screw is an ancient device used to lift water from one location to another. They are so useful that they are still in widespread use today! After a quick trip to the hardware store, you can build your own Archimedes screw in this fun activity.
Materials
- PVC pipe, at least 1 inch outer diameter
- Clear vinyl tubing, at least 1/4 inch inner diameter
- Duct tape
- Scissors
- Containers for water (2)
- Something to elevate one of the containers, like a small box or a third container
- Optional: food coloring
Prep Work
Instructions
- Attach one end of the vinyl tubing to one end of the PVC pipe with duct tape.
- Tightly wrap the tubing around the pipe in a spiral.
- Attach the tubing to the other end of the pipe with duct tape.
- 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.
- Fill one of your containers with water. Add food coloring to make the water easier to see when it is in the tubing if you wish.
- 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, 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 way.
- Keep spinning and watch as the water moves up into the higher container!
- Experiment with 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?
What Happened?
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.
Digging Deeper
The Archimedes screw was invented by Archimedes, an ancient Greek scientist. It was originally used to pump water out of the hull of a large ship to prevent it from sinking. Eventually its use expanded to other applications, like moving water from low-lying bodies of water to higher irrigation ditches, or moving other liquids like chocolate! The simple design is so effective that it is still used in modern-day applications, such as moving wastewater at treatment plants because they do not clog easily. For more information about the history, science, and modern uses of the Archimedes screw, see the link in the Additional Resources section.
Ask an Expert
For Further Exploration
- Experiment with the design 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?
