Earth Science



ESS Unit 3 Earth’s Rotation Name _______________________Period ___________

Part 1 The Stars

1. Observe the motion of the stars during the night in the video clip:

2. Describe your observation on the POM chart below.

|Essential Question: What evidence is there that the Earth is rotating on its axis? |

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|PHENOMENON: |OBJECTS: |MOTION: |

|What did you observe? |Define the system. |Describe the motion that in the model that explains your |

|What evidence do you have? |What objects are |observations |

| |interacting? | |

| |Stars as seen from Earth | |

| |throughout the night | |

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| |Big Dipper clock | |

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| |Global winds: Coriolis | |

| |Effect | |

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| |Foucault pendulum | |

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|Summary Statement: We know that the Earth is rotating on its axis because we observe…. |

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Directions:

1. Cut-out and assemble the dipper clock or view the simulation above.

2. Turn the outer circle of the dipper clock so the current month is at the TOP of the dial.

3. Turn the inner dial until the Big Dipper matches the direction of the Big Dipper in the diagram below.

4. Look at the notched window and determine the time. Label the diagram below with the time.

5. On your diagram, sketch the position of the Big Dipper at 1 am. Label it with the time.

6. Sketch and label the positions of the Big Dipper at 4 am, noon and at 9 pm.

7. Draw an arrow to show the direction that the Big Dipper is moving as it circles around Polaris.

8. Add the Little Dipper to your diagram

[pic][pic]

1. Describe the orientation of the Big Dipper on a June evening at 9 pm.

2. How long does it take the Big Dipper to make one complete revolution around Polaris?

3. Explain why the Big Dipper is considered a circumpolar constellation:

4. What are some other circumpolar constellations?

Part 2: Coriolis Effect

1. Each pair of students obtain a wipe-off globe and marker. Draw a line on the globe around the equator (0().

2. Without spinning the globe, Slowly draw a straight line from the equator to the North Pole (90() and back to the equator. This is the direction that winds would blow if the Earth did NOT rotate.

3. Repeat and draw a STRAIGHT LINE, but this time have your partner SLOWLY SPIN the Earth counter-clockwise. Describe your observation of the ‘winds’ on your POM chart.

1. The winds in the Northern Hemisphere were deflected to the (right, left) CIRCLE THE CORRECT ANSWER and in a (west, east) direction.

Part 3: Foucault’s Pendulum

1. Observe the video clip of a pendulum for several minutes.

2. Describe your observations in on the POM chart.

1. Has the pendulum changed direction relative to the background?

2. Is the pendulum changing directions or the Earth? Explain

3. How long will it take for the pendulum to know down all of the pins?

Part 4: Calculating Rotational Speed of the Earth

1. Obtain a long rope that is approximately 10 meters long.

2. One student will represent the North Pole and hold one end of a rope in the middle of an open area.

3. A second student will hold the other end of the outstretched rope and represent the equator.

4. A third student will hold the middle of the outstretched rope and represent a location such as Minneapolis, Minnesota at latitude of 45° N.

5. With the rope outstretched, the students will trace out one complete circle in 24 seconds.

6. Using the formula to find circumference, calculate the distance walked for each student. C = 2 π r

7. Use the formula SPEED = DISTANCE /TIME to calculate the SPEED for each location

|Location |Latitude |Radius (m) |Distance (m) |Time (sec) |Speed (m/s) |

| | |(rope) |C = 2π r | |s = d/t |

| | | | |24 | |

| | | | |24 | |

| | | | |24 | |

Using the information below, complete the table for the speed of Earth’s rotation at different locations

|Location on Earth |Latitude (degrees) |Distance (km) |Time (hrs.) |Speed (km/hr) |

|North Pole | | |24 | |

|Minnesota |45 | |24 |1300 |

|Equator | |40,074 |24 | |

Conclusion: Do all locations on earth rotate at the same rate?

How is rotational speed dependent on latitude?

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