DIY WIND METER

" Research is what I'm doing when I don't know what I'm doing."- Wernher von Braun

Did you know that wind is caused from the difference in air pressures. Here is a fun experiment for students who want to learn how to measure wind speed by creating an anemometer. Students can observe the affects of different wind speeds on an anemometer.

Materials:

• Five three-ounce paper cups

• Paper hole punch or sharpened pencil

• Ruler

• Two straws

• Pin

• Stapler

• Pencil with eraser

• Fan with different speeds(optional)

• Timer(optional)

Instructions:

1. Make a hole in the side of 4 cups.

2. Make 4 holes evenly spaced around the rim of the fifth cup and one hole in the middle of the base of the cup. The fifth cup with four holes will be the center of our anemometer.

3. Take a straw and push it through one of the holes made in one of the one-holed cups till about 1 inch of the straw is inside the cup.Staple the end the straw to the side of the cup. Repeat this procedure with another cup.

4. Take one straw with a cup attached and push the straw through the one of the holes in the 5-holed cup(open side up). The straw should be pushed through the hole and out the hole on the opposite side from where it was inserted. Repeat the same with the second straw with the cup attached to it.

5. Add one cup to each end of the straw, turn the cups so that they all face the same direction, and staple the end of the straws to the sides of the cup. There should be four cups that have straws forming an X and one cup in between them.

6. Make sure that all the cups are the approximately the same distance form the center cup. Carefully push a pin through the two straws that intersect at the center. Take a pencil,eraser side up, and push it through the hole in the base of the 5-holed cup. Gently push the pin into the eraser.

7. Now your anemometer is ready to observe and experiment with.

8. You can observe what happens when you hold the anemometer in front of fan at different speeds or take it outside to see the speed of the wind at that time.

Science Behind It:

• The air is made up of tiny molecules that hit objects when the wind hits something. Have you noticed that when the wind speed is higher, it hits objects harder? That shows us that there are many molecules at a faster speed that are hitting at the objects. The cups on the anemometer move quicker while experiencing a faster, and stronger wind while during a slower wind, the cups will no t move as much.

• Bonus Challenge(calculating the actual mph(miles per hour) of the wind that is measured by your anemometer):

• To calculate the actual speed of the wind, first determine what the circumference of your anemometer. To determine the circumference you can use the formula Circumference= 2πr in inches or you can take a string to measure the distance around the circle. Convert this number into miles by multiplying it by 5280, the number of feet in one mile). The multiply that value by rpm(revolutions per minute) which can be calculated by finding out how many complete turns made by the cup for one minute. Divide this product by 60 since you want to convert the minutes to hours. This would be the approximate miles per hour the anemometer is spinning(does not take friction into account).