Warming up with wheels: Why were wheels so important in history? What can one do better with a wheel? Play with wheels and write down 5-10 things that wheels can help you do. The pictures below can give you a hint or two.
Introduction:
For thousands of yuears people have used the pushing power of water to drive machines. Early wheeled vehicles were pushed or pulled by people and animals. Since Roman times wooden waterwheels have powered millstones to grind corn. Later, waterwheels became the main power source for industry. The modern day water turbine was developed from the waterwheel.
All waterwheels direct water around wheel blades to start the wheel spinning. Water creates its own pressure due to its weight. Energy from fast-flowing water turns a waterwheel. The constant movement from the revolving wheel can then be put to work. You can harness the work from your water wheel to raise a bucketful of water.
Materials:
- small (590-ml) plastic soda bottle
- large (2-L) plastic soda bottle
- scissors
- straw
- hammer and punch
- toothpicks
- pencil
- tape
- large screw-type bottle cap
- glue
- 0.5 meters of kite string
- sink with running water
- small weights
- paper towels (just in case!)
Classroom Management:
Students should build their water wheels in small groups of 3-5 students. Teachers may wish to have stations with materials already cut for student construction. If it is too difficult to obtain the materials, one waterwheel can be made for demonstration to the entire class.
Activity Steps:
Imagine talking to people on top
of a mesa who are tired of bringing up water from the stream
at the foot of the mesa. They want you to design a way to save
them the trip. The first step is to design and build a water
wheel that will life water out of a stream and dump water into
a bucket. Later you will have a chance to design a system of
lifting water up to the mesa dwellers. Make
a drawing of your water wheel.
Design challenge : Power of a Waterwheel
- Cut out the bottom of a small plastic soda bottle. Cut out five evenly-spaced flaps around the sides of the bottle and fold them as shown.
- An adult should punch a hole in the bottom of the waterwheel with a punch and hammer. Insert a straw through the hole so that it freely rotates.
- Cut the side of the large plastic soda bottle large enough to place the waterwheel inside. Place two holes on either side of the soda bottle for the straw to pass through.
- Place the waterwheel inside the bottom of the large soda bottle. Carefully ease the straws through the holes and secure with toothpicks.
- Make two holes in the top of the large soda bottle and insert the pencil. Tape a short piece of straw under the end of the pencil.
- Make a bucket from the bottle cap. Glue a matchstick across the top. Tie it to around a 0.5 meter of string. Feed the string through the short piece of straw on the pencil and tie it to the closest waterwheel straw.
- Place the entire apparatus inside the sink. Direct the flow of the faucet down the mouth of the large plastic bottle. Slightly turn the faucet on.
Watch the water wheel work as the falling water hits the blades.
1) What happens to the bucket when it is empty? ...filled with water?
2) Try putting a small weight in the empty bucket. Does the bucket still rise?
3) What happens if you increase the force of the water from the faucet in a sink? Does the wheel do more work? [Niagara Falls versus a small creek]
4) What happens if you increase the distance that the water falls on the wheel? [Hint: The further the water has to fall, the more stored energy it has.]
Discuss with your group and then write a few sentences describing the relationship between force and distance with wheels.
Extensions:
