Strong Wind Science: The Power of a Pinwheel
Have you ever ridden your bike into a strong wind? If so, did your legs feel like lead? How does this compare to how you feel when the wind is pushing against your back – does that make you feel ready for the Tour de France? In this science activity, you will explore how wind-powered devices, like wind turbines and pinwheels, also react in different ways to the direction of the wind.
This activity is not appropriate for use as a science fair project. Good science fair projects have a stronger focus on controlling variables, taking accurate measurements, and analyzing data. To find a science fair project that is just right for you, browse our library of over 1,200 Science Fair Project Ideas or use the Topic Selection Wizard to get a personalized project recommendation.
Wind turbines are machines that change the energy in wind into mechanical energy or electrical energy. Windmills are examples of wind turbines that convert wind energy into mechanical energy. The Netherlands is a country well-known for its windmills that have been used for centuries to grind corn, drain land, and cut wood. Wind farms, on the other hand, are examples of wind turbines that convert wind energy into electrical energy. In California, you can see rows of wind turbines along windy ridges and mountain passes. The wind turbines on these wind farms connect directly into power grids and produce five percent of the electricity that the entire state uses.
A wind turbine has a rotor with blades that is connected to a shaft. As wind energy hits the blades, the rotor turns, which causes the shaft to turn as well. As the shaft turns, it is able to do work and produce either mechanical or electrical energy. The more wind that hits the blades, the more the rotor can turn and the more energy the wind turbine can produce.
Extra: Try repeating this activity with a few different pinwheels. Do you get the same results for each pinwheel?
Extra: If you want a more challenging activity, you can try to quantify how much power the pinwheel makes when it is blown on from one direction compared to another direction. To do this, you will need to attach the pinwheel blades to a fixed shaft (e.g., wooden skewer) so that they rotate the shaft when they are blown on. Support the shaft by putting it through a cardboard oatmeal canister or similar object. On the other end of the shaft, tie a piece of thread with small weights (e.g., paper clips) on it. When the pinwheel is blown on and the shaft turns, it should pull up the weights. For more details on how to create this setup, see the Science Buddies project idea in the “More to explore” section. How much power do you think your pinwheel can produce?
Observations and Results
When you blew straight onto the front of the pinwheel did it spin counterclockwise? Did it spin best when you were blowing into its “cups”?
Most pinwheels have the blades arranged so that when wind blows straight at them, they spin counterclockwise. This is because the blades’ “cups” are made so that the oncoming air is captured and pushes the blades in this direction. (You can try looking at several different pinwheels to see this pattern shared among them.) When wind is blown into the cups, the pinwheel spins well. Consequently, if you are using a typical pinwheel, turn it so that the front side is facing your right, and blow into the side of the blades, the blades will spin quickly counterclockwise if you blow on the bottom half (into the cups) but will spin slowly clockwise if you blow on the top half (against the backs of the cups). Similarly, if the pinwheel’s front side is facing your left and you blow into the side of the blades, they will spin quickly counterclockwise if you blow on the top half (into the cups) but will spin slowly clockwise if you blow on the bottom half (against the cups’ backs). If your pinwheel were a wind turbine, and spinning counterclockwise turned the energy of the wind into electrical energy, then when wind is blowing directly into the cups it would most efficiently produce electrical energy.
More to Explore
Teisha Rowland, PhD, Science Buddies
Science Buddies |
Energy, power, forces, machines
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