Class Copy

Earth Model

Background

The Earth's structure, scale and our place on it can be difficult to comprehend. Today we will use baker's clay to create a physical model of the planet. We will also use the idea of normalized data.

At times it is difficult to visualize the relationships among numbers if they are in an inconvenient form. The data table on the left contains a list of measurements. This raw data can be converted into a form that is easier to understand by dividing all the measurements by the value of the smallest (as shown in the second table on the right). This process is called normalizing the data. Now it is easier to see the third measurement is 19 times larger than the first measurement.

Raw Data (mm)
0.0625
0.125
1.1875
0.875
Raw Data (mm) divided by = normalized data
0.0625 0.0625 1
0.125 0.0625 2
1.1875 0.0625 19
0.875 0.0625 14

Materials:

· Data sheet · Triple-beam balance · Baker's clay · Fishing line · Metric Ruler

Materials Table:

Layer Actual Width
(km)
Actual Volume
(x 109 km3)
Mass of clay in model (g)
Inner core 1216 7.5 2
Outer core 2270 170 46
Mantle 2885 906 242
Crust 5 to 40 21 6

Construction Procedure:

  1. We will assemble the Earth model one layer at a time, starting with the inner core.
  2. Obtain a small amount of the Baker's clay for the inner core. The color is your choice.
  3. Using a triple-beam balance, measure out exactly 2 grams.
  4. Return the remainder.
  5. Roll the clay into a sphere.
  6. For each subsequent layer, follow this process:
    1. Obtain a small amount of the appropriate clay.
    2. Using a triple-beam balance, measure out the exact amount.
    3. Return the remainder.
    4. Carefully mold the clay into an even layer around your Earth model.
  7. When finished, measure the mass of your Earth model and record.
  8. Measure the circumference of your Earth model and record.
  9. Use a sawing motion with a taut length of fishing line to saw through the Earth model.
  10. Measure and record the thickness of the layers in your Earth model. You may have to estimate what the average thickness is if the model is not uniform.
  11. Present both halves of your Earth model to the instructor.