An anemometer is the instrument used to measure wind speed. Here is how to make one at home.
- 5 paper cups
- 2 straws
- Pencil with eraser
- Hole punch
Steps to make the anemometer:
- Take one paper cup and punch 4 holes just below the rim. They should be evenly spaced.
- Take the remaining 4 paper cups and punch two holes in each cup just below the rim. The holes should be directly across from each other.
- Take the cup with four holes and push the two straws through the holes. Making an ‘X’ in the middle of the cup.
- Take the four remaining cups and thread the straws through the two holes.
- You want all of the cups facing the same direction.
- To attach the cups to the straws, bend the straw and tape it to the side of the cup.
- Poke a hole through the bottom of the center cup that has four holes.
- Press the pencil through the hole, eraser first.
- Take the pin and push it through the straws into the eraser.
Here’s how to calculate what the actual speed of the wind is in miles per hour:
- First you must calculate how many revolutions you have per minute (RPM). Either use a different colored cup, or put a marking on one of the cups so you can county how many times that cup goes around in one minute.
- Find the circumference of the of the circle made by the rotating cups. Measure the distance from one cup to the cup directly across from it. Multiply by the value of pi (3.14).
- Convert this to feet by dividing the circumference by 12.
- Multiply that number times your RPM. This will give you a wind speed per minute.
- Convert this value to distance per hour by multiplying by 60.
- To convert this distance from feet to miles per hour, divide by 5,280.
To learn how to make a wind vane check out this edition of Weather for Kids.
To learn how to measure the wind speed with a flag watch this edition of Weather for Kids.