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# Earth Model for Journal

## Background

The Earth's structure and scale can be difficult to comprehend. Today we will use data to make a numeric representation of the Earth's structure and then make a physical model of the planet with clay.

### Raw Data

Raw Data (mm)
0.0625
0.125
1.1875
0.875

At times it is difficult to visualize the relationships among numbers if they are in an inconvenient form. The data table on the right contains a list of measurements. Decimal numbers can be confusing. This raw data can be converted into a form that is easier to understand. This process is called normalizing the data.

### Normalized Data

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

To normalize the data, some calculation is performed on all the measurements. In this case, we divide all the measurements by the value of the smallest. The second table shows the normalized data. Now it is easier to see the third measurement is 19 times larger than the first measurement.

### Normalizing the Earth Layer's Thicknesses

Earth Layer Thickness (km) Thickness (normalized)
Inner core 1210 35
Outer core 2260 65
Mantle 2885 82
Crust 35 (varies) 1

This table shows the thicknesses of the Earth's layers. The actual thicknesses in kilometers are useful, but normalizing the data may make the relationships more obvious. To normalize we divide all the thicknesses by the smallest thickness (crust). Now we clearly see that the mantle is 82 times thicker than the crust!

### Normalizing the Earth Layer's Volume

Earth Layer Volume (x 109 km3) Volume (normalized)
Inner core 7.42 1
Outer core 168
Mantle 885
Crust 17.7

The table to the right shows the volumes of each of the Earth's layers. Copy and complete this table in your journal. Show your calculations in your journal. From the normalized data you will see that the Earth's mantle makes up the vast majority of the Earth.

## Physical Model

We can see from the numeric analysis that the inner core and crust are small compared to the mantle. There is another observation that is best discovered by making a physical model of the earth using clay.

## Materials

 a. Triple-beam balance b. Baker's clay c. Fishing line d. Metric Ruler

## Procedure

1. Record the following data table in your journal.
Layer Clay color Clay mass (g) Layer thickness of model (measured in cm) Layer thickness of model (normalized)
Inner core   2
Outer core   46
Mantle   238
Crust   5
2. We will assemble the Earth model one layer at a time, starting with the inner core.
3. Measure exactly 2 grams of the Baker's clay for the inner core. Record the color you've chosen in the data table.
4. Roll the clay into a sphere. This is the inner core.
5. Measure 46 grams of the Baker's clay for the outer core. Record the color you've chosen in the data table.
6. Carefully mold the clay into an even layer around the inner core. The inner core should be in the exact center of the outer core layer you just applied. This is important!
7. Repeat steps 5 and 6 for the mantle and crust. Use the masses shown in the data table.
8. When finished assembling the model, measure and record in your journal the total mass.
9. Measure and record in your journal the circumference of your Earth model.
10. Use a taut length of fishing line to slice through the center of the Earth model. A sawing motion may work best.
11. Present both halves of your Earth model to the instructor.
12. Measure and record in your journal the thickness of each layer in your Earth model. You may have to estimate what the average thickness is if the model is not uniform.
13. Calculate the normalized thicknesses of the Earth's layers. Divide all the thicknesses by the smallest thickness (crust). Record in your journal. Show your calculations!