## Introduction: Anemometer

Introduction:

• An Anemometer is a device used to measure wind speed in weather station.
• It uses cup like shapes to catch the wind, causing the device to spin.
• How many times it spins in a given interval of time can tell how fast the wind is moving.
• The term ANEMOMETER is derived from Greek word named ANEMOS meaning wind.
• A cup anemometer is a basic kind of device while more accurate anemometer use lasers and ultrasonic measuring technology.
• English astronomer John Robinson invented four cup anemometer in 1846.
• Here I have made a working three cup anemometer to make students understand the concept behind working of Anemometer.
• Do try it. Learning by making project.

Time required: 45 minutes

Group size: 2

Summary: Students create their own anemometers-instruments for measuring wind speed. They see how an anemometer measures wind speed by taking measurements at various school locations.

Materials needed:

1. A cardboard for base

2. Modelling clay( a small piece)

3. styrofoam or paper cup (1)

4. Plastic balls (2)

5. Plastic Straw (1)

6.Skewer (length 15 cm approx)

7. Toothpick (4)

8. Scissor (1)

9. Cutter (1)

10. Circle master

## Step 1: 1.Making a Base

1, Take a cardboard piece as base and glue a sheet of paper.

2. Use a modelling clay to hold a straw in vertical position as shown in the image.

3. Take any styrofoam or paper cup and poke a hole at the center in such a way that the straw can easily be inserted.

4. Glue the tip of the cup and insert the straw.

5. The cup gets sticked to the cardboard and hence the base of an anemometer is ready.

## Step 2: Making a Rotating Section

1. Take two thin plastic balls (easily available in kids toy shop) and cut them in half using a cutter and hand gloves (Safety first).

2.You will get four hemisphere balls.

3. Take one of the hemisphere ball and mark points at 0, 120 and 240 degrees using a circle master.

The three marked points should 120 degree apart from each other.

4. Poke a hole on the marked points.(total 3 holes)

5. Insert one toothpick in each of the three holes as shown in image.

6. Poke 1 hole in each of the remaining balls and insert in the other end of toothpick in such a manner that the balls are facing in same direction. WHY? So that the air can fill the cup and make it rotate in one uniform direction. If balls are arranged randomly in any direction the model fails to spin.

7. Connect a skewer at the center of ball as shown in the image.

8. The rotating section is ready to use.

## Step 3: Arranging the Working Model

From step 1 and step 2 we have:

A base and a rotating part

Insert the skewer of rotating part in the straw of the base.

Use a fan to test its working.

The rotating part should freely move.

## Step 4: Arrangement to Count Number of Rotations

Making a working model is just half work done.

To understand the concept we need to practically test it and apply the physics behind it.

To count the number of rotations mark one of the hemisphere cup with a coloured tape.

## Step 5: The Final Calculation of Wind Speed

Wind speed = Circumference x Number of rotations

The detailed calculation is shown in the image.

Thankyou

## Step 6: Video: How to Make an Anemometer and How an Anemometer Works

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