Coriolis Effect (Jennifer Kim)

Principles

1. Coriolis Effect

2. Foucault Pendulum

Standards

HS-ESS2-2 Analyze geoscience data to make the claim that one change in the Earth's surface can create feedbacks that cause changes to other Earth systems.

HS-ESS2-4 Use a model to describe how variations in the flow of energy into and out of Earth's systems results in changes in climate

HS-ESS2-6 Develop a quantitative model to describe the cycling of carbon among the hydrosphere, atmosphere, geosphere, and biosphere

Materials needed

There are companies that have demonstration equipment that also illustrate Coriolis Effect such as Flinn Scientific. The one that is highlighted on this page is no longer manufactured.

Procedure

Coriolis Effect-Northern Hemisphere1. Raise the end of the guide bar from its storage position, pivot it over the center post and press into position on top of the post.

2. Place the unit on the stage of the overhead project or the Elmo and project the demonstration equipment onto the screen.

3. Orient students by explaining that they are observing the earth as if they were out in space looking down directly over the North Pole.

4. With the marking pen along one side of the guide, draw a straight line on the map from the North Pole to the equator without moving the map. Explain to the students that this straight line would be the path of a moving object from the pole to the equator if the earth were not rotating.

5. Ask student what effect the earth's rotation would have on the path of an object moving from the Pole to the equator.

6. To test the student hypotheses, rotate the map in a counterclockwise direction as indicated by the arrows along the edge.

7. While rotating the map with one hand, draw a straight line with the other by running the marking pen along one side of the guide from the center outward.

8. Point out to the students that the guide was used to draw a straight line. Students will see that the line drawn while the map was rotating is curved or has a sidewise drift in relation to the earth.

9. The students should develop the concept that in the Northern Hemisphere, the curve is always to the right as you look in the direction of the object's movement.

Foucault Pendulum Over the North Pole

1. The guide bar should be swung away from the center post to its storage position.

2. Insert the snap-in fitting on the base of the pendulum mount into the hole at the edge of the map. The pendulum bob should rest over the North Pole, slightly above the poast.

3. Place the unit on the stage of the overhead project or the Elmo and project the demonstration equipment onto the screen.

4. Turn the map so North America is located at the bottom of the screen. Set the pendulum in motion, swinging in a north-south direction relative to North America (vertically on the screen).

5. Next, slowly rotate the map 90 degrees in a counterclockwise direction as indicated by the arrows along its edge, simulating the rotation of the earth.

6. At this point the swing of the pendulum will be east-west relative to North America even though the pendulum is still swinging in the same plane (vertically on the screen).

7. Point out that to a person sitting on the map in North America the pendulum has changed its direction of swing from north-south to east west, its apparent change of plane caused by the earth's rotation.

8. Ask students what the apparent direction of the pendulum's swing would be if the earth (map) were rotated 180, 270, or 360 degrees.

Explanation

A) Coriolis Effect

According to Newton's Law of Motion an object will continue in uniform motion in a straight line unless acted upon by a net outside force. In the diagram below it appears that this law has been violated. The solid line represents the path of a missile fired due south toward New York from the North Pole. When plotted on a map the flight path of the missile is curved to the west. It is not straight as the first law of motion demands. The missile lands not in New York but near Chicago.