Anemometer

Meteorologists use anemometers to measure wind speed in one area. With this data, they can determine how quickly a storm, or weather system, will travel to other areas.

Use the materials and follow the directions below.

Materials
• Five 3-ounce paper cups
• Hole punch
• One straight pin
• Pencil (with eraser)
• Scissors
• Stapler
• Two straight plastic straws
• Watch with a second hand

Directions

1. Punch one hole in each of four paper cups, about ½" below the rim. Color the outside of one of the cups.
2. In the fifth cup, punch four evenly spaced holes about ¼ " below the rim.
3. Push a straw through the hole of the colored cup. Fold down the tip of the straw inside the cup, and staple it to the cup on the side opposite the hole.
4. Push the straw through two opposite holes in the four-hole cup. Attach another cup to the opposite end of the straw. Make sure that the second cup faces the opposite direction from the first cup.
5. Repeat the above step with the other two cups and straw.
6. Position the four cups so that they face the same direction — clockwise or counterclockwise. Make sure the cups are all the same distance from the center.
7. Poke a hole in the bottom of the center cup. Push the eraser end of the pencil through the hole.
8. Push the pin through the intersection of the two straws. Then push it into the eraser as far as possible.

Experiment!

1. With a friend, take the anemometer outside to an open area where the wind is blowing.
2. While one of you times exactly one minute on the watch, the other counts how many times the colored cup goes by in one minute. This is the number of revolutions per minute (RPM).
3. Convert your answer for RPM to miles per hour (MPH) using this formula:
RPM X 0.2142 = MPH
4. Record this number on your Weather Data Sheet (PDF).