Anemometer Lesson Outline

The original version of this page is from a document Grace and Ned made to get a grasp on what we'd be asking TTI students to do in their first lesson.

1. Make the anemometer. (This will probably need a lot of pictures to explain it)
2. Get it moving (either on the back of a bike, or with wind, not by blowing on it)
   • Record the most common voltage and the highest one on the website/printout.
3. Come back inside: a timekeeper should let everyone know when a minute is up while everyone else tries to make the most common voltage they saw outside and counts revolutions.
4. Do the same thing but try and make half the voltage.
5. Everyone divides the voltage of each trial by the RPM. The numbers should be similar; if they’re not, then try making the same two voltages again.
6. That number? It’s k_V! Calculate what RPM you’ll get to make some voltage near what you’ve already tested.
7. So what rpm was it moving at the highest Voltage you measured?
8. Now a geometry problem: given that what’s important is the center of the cup, you know the size of the racetrack; the previously computed RPM is how many laps it does per minute. So how fast is the ‘racer’ moving?
9. That’s the wind speed (this could use a convincing illustration, I think).
10. Finally, measure the speed at which you can pedal a bike, or the wind speed around your house.

• brief illustration of “catching the wind”: very simple pic of an anemometer moving as the wind pushes it. Should show crossbar, short shaft, motor, and very simple cups.
• focus in on the cups - they have to catch the wind, they have to all be in the same direction. Again, very simple drawing of anemometer. Perhaps use arrows to show directions of cups.
• Draw a few examples of “things that could be cups” or even “shapes that could be cups”
• Drawing for construction suggestions - how shaft should fit onto motor (glue? pin? etc). All shaft/cups/motor should move at once.

• picture of anemometer hooked up to voltmeter
• picture of testing on bike
• picture of testing in wind

• picture of the exercise - one dude keeping time, others turning, looking at voltage
• possibly with a “counting spiral” for counting revolutions

• Racetrack analogy illustration.Compare dude on a racetrack (SEE HIM RUN IN A CIRCLE) with cup on anemometer (SEE IT MOVE IN A CIRCLE).
• Happy limb figures measuring wind in general